Poland VAT Invoice Requirements: Complete Guide to All 10 Types

Every Polish VAT invoice must satisfy 11 mandatory data elements defined by Article 106e of the VAT Act (ustawa o VAT): issue date, sequential number, supplier and customer names with their NIP tax identification numbers, a description of goods or services with quantities, transaction date, net unit price, applicable VAT rate, the VAT amount, a rate-by-rate breakdown, and the gross total. Poland's VAT framework recognizes 10 distinct invoice types, each carrying its own additional requirements beyond these baseline fields.

This guide covers the full scope of Poland VAT invoice requirements from the receiver's perspective. It walks through mandatory fields under Article 106e, all 10 Polish invoice types and what makes each one unique, currency and language rules for cross-border transactions, KSeF (Krajowy System e-Faktur) mandatory e-invoicing status by type, retention deadlines, and a practical verification checklist for validating received Polish invoices. While there are common invoice types used in international business that share structural similarities across jurisdictions, Poland's system is notably granular in its classification and field-level requirements.

The perspective throughout is AP-focused. Rather than explaining how to issue Polish invoices, this reference is built for finance professionals, accountants, and accounts payable teams who need to confirm that Polish invoices they receive contain all legally required elements before approving them for payment or booking them into their systems.

The foundation of Polish invoice compliance starts with the mandatory data elements that every standard VAT invoice must carry.

Mandatory Fields Under Article 106e of the VAT Act

Article 106e of the Polish VAT Act (ustawa o VAT) defines 11 data elements that must appear on every standard VAT invoice issued in Poland. If you receive invoices from Polish suppliers, each document should contain the following fields.

Date of issue. The calendar date on which the invoice was created. This appears near the top of the document and establishes when the seller's invoicing obligation was fulfilled.
Unique sequential invoice number. A number that unambiguously identifies the invoice within the seller's numbering series. Polish businesses may use multiple numbering series (by month, branch, or type), but each number must be unique within its series.
Supplier's full name, address, and NIP. The seller's registered business name, legal address, and 10-digit tax identification number (NIP, or Numer Identyfikacji Podatkowej). For intra-EU transactions, the NIP is prefixed with "PL" to form the EU VAT identification number.
Customer's full name, address, and NIP. The buyer's registered details and NIP, where applicable. For domestic B2B transactions, the buyer's NIP is required. Consumer invoices and certain cross-border supplies follow different rules.
Description of quantity and type of goods or services. An itemized description of what was supplied, including quantities and units of measure. AP teams should verify that each line item corresponds to what was actually received.
Date of transaction or payment. The date the goods were delivered or services completed, or the date advance payment was received, if that date differs from the issue date. When these dates match, some invoices carry a notation such as "date of supply: as date of issue."
Unit price exclusive of tax. The net price per unit after applying any discounts, rebates, or reductions agreed between the parties.
VAT rate applied. The applicable VAT rate for each line item. Poland uses multiple rates, so a single invoice may carry items at different rates.
VAT amount payable. The calculated tax amount for each line item or rate grouping, expressed in Polish zloty (PLN).
Breakdown of VAT by rate or exemption. A summary section grouping net amounts, VAT amounts, and gross amounts by each rate or exemption basis. This breakdown is essential for accurate VAT recovery.
Net value and gross total. The total net amount (before tax) and the total gross amount (including tax) for the entire invoice.

Poland's Four VAT Rates

Polish VAT invoices apply one of four rates to each line item:

23% standard rate. Applies to most goods and services and is the rate you will encounter on the majority of invoices.
8% reduced rate. Covers specific categories including food products, pharmaceutical goods, construction services, and tourism-related services.
5% reduced rate. Applies to basic foodstuffs, books, and periodicals.
0% zero rate. Reserved for exports and intra-Community supplies of goods. The 0% rate is conditional: the seller must hold documentary proof that the goods left Poland or were transported to another EU member state.

Separately from these four rates, certain supplies are VAT-exempt (zwolnienie z VAT) under the Polish VAT Act. Exempt invoices carry an exemption notation (commonly "zw.") and reference the legal basis for the exemption rather than showing a percentage rate. If you receive an invoice marked "zw." instead of a rate, verify the exemption basis before processing.

Invoice Timing Rules

Polish tax invoice rules impose strict deadlines for when invoices must be issued:

General rule: The invoice must be issued no later than the 15th day of the month following the month in which the goods were delivered or the services were performed.
Advance payment invoices: When a payment is received before the supply takes place, the invoice must be issued by the 15th of the month after the advance payment was received.
Construction services: A special deadline applies. Invoices for construction work must be issued within 30 days from the date of completion or handover of the construction service.
Early issuance limit: Invoices cannot be issued more than 60 days before the supply of goods, performance of services, or receipt of payment.

These timing requirements affect how quickly your AP team can expect to receive invoices from Polish suppliers and influence when the right to deduct input VAT begins.

Strict compliance with these Polish invoice mandatory fields is not optional. According to PwC's tax summary for Poland, customs-tax audits in 2024 detected irregularities in nearly 94% of cases, revealing losses exceeding PLN 10.3 billion and underscoring why the government requires strict VAT invoice documentation from all registered businesses. An invoice missing any of the 11 mandatory elements can be rejected by tax authorities, potentially blocking your right to deduct the input VAT shown on that document.

These 11 fields and timing rules apply universally, but Poland recognizes 10 distinct invoice types, each carrying additional requirements and special fields beyond the standard set.

All 10 Polish Invoice Types and Their Requirements

Polish VAT law recognizes ten distinct invoice types, each serving a specific commercial or regulatory purpose. While the standard VAT invoice accounts for the majority of B2B transactions, AP teams and accountants processing Polish invoices will encounter other types depending on the nature of the supply, the parties involved, and the timing of payment.

Below is a detailed reference for each type, including its purpose, any additional mandatory elements beyond the standard fields covered in Article 106e, and its status under KSeF.

1. Standard VAT Invoice (Faktura VAT)

The standard VAT invoice is the primary B2B tax document in Poland and the type AP teams encounter most frequently. It must contain all 11 mandatory fields required under Article 106e of the VAT Act, including full seller and buyer identification, NIP numbers, itemized goods or services with quantities, applicable VAT rates, and net and gross amounts.

From 2026, all standard VAT invoices must be issued and transmitted through KSeF in structured XML format. For AP purposes, this means every standard invoice from a Polish supplier should carry a KSeF identification number that can be verified against the national system.

2. Corrective Invoice (Faktura Korygujaca)

A corrective invoice is issued to fix errors on a previously issued invoice, whether the error relates to price, quantity, VAT rate, or other material data. Polish VAT law requires that the corrective invoice clearly reference the original invoice number and date, identify which data points are being corrected, and state the corrected values.

Under KSeF, corrective invoices must also reference the original invoice's KSeF identification number, creating a traceable correction chain within the system. Buyers can now propose corrections through KSeF as well, which shifts part of the correction workflow to the recipient side. AP teams should retain both the original and corrective invoices and ensure the correction is reflected in their VAT settlement for the appropriate period.

3. Correction Note (Nota Korygujaca)

Correction notes were historically issued by the buyer to fix minor formal errors on received invoices, such as address misspellings or incorrect postal codes. The seller had to accept the correction note for it to take effect.

Important: Correction notes are no longer valid as of February 1, 2026. The KSeF system replaces them entirely with corrective invoices issued through the platform. AP teams should be aware that they may still encounter legacy correction notes linked to transactions that occurred before the February 2026 cutoff. For any new corrections, the proper instrument is now the corrective invoice.

4. Pro Forma Invoice (Faktura Pro Forma)

A pro forma invoice is a preliminary cost estimate or price quotation. It is not a tax document under Polish VAT law, does not create any VAT obligation, and cannot be used to claim input VAT deductions.

Pro forma invoices fall entirely outside the scope of KSeF. Treat these strictly as informational documents and never process a pro forma as a valid tax invoice. If a supplier later issues a standard VAT invoice or an advance payment invoice for the same transaction, that document is the one with legal standing.

5. Simplified Invoice (Faktura Uproszczona)

Polish law permits simplified invoices for transactions where the gross amount does not exceed PLN 450 (or EUR 100). These invoices carry reduced mandatory field requirements, most notably that buyer identification details (name, address, NIP) are not required.

Simplified invoices cannot be used for intra-Community supplies, distance sales, or transactions where reverse charge applies. Through the end of 2026, they can still be issued conventionally outside of KSeF. For AP teams, the reduced detail on simplified invoices means that matching them to purchase orders or vendor records may require additional context from internal procurement data.

6. Margin Invoice (Faktura VAT Marza)

Margin invoices apply to a specific set of transactions where only the seller's margin is subject to VAT rather than the full transaction value. These include sales of second-hand goods, travel agency services, works of art, antiques, and collectors' items.

A margin invoice must carry the annotation "VAT marza" (or the specific statutory phrase corresponding to the transaction type). Critically, no separate VAT line appears on the invoice because the tax is calculated on the margin alone. AP teams receiving a margin invoice should not expect to see a standard VAT breakdown and should note that input VAT recovery may be restricted depending on the goods or services involved.

7. RR Invoice (Faktura VAT RR)

The RR invoice documents purchases from flat-rate farmers (rolnik ryczaltowy) and has a unique characteristic: it is issued by the buyer, not by the farmer. This reversal of the normal invoicing flow means the purchasing entity bears responsibility for creating a compliant document.

The invoice must carry the "VAT RR Invoice" marking and include the farmer's signed declaration confirming their flat-rate farmer status. The farmer receives a 7% flat-rate VAT return on the transaction value. RR invoices remain optional in KSeF until at least April 2026, so AP teams may receive these in either paper or electronic form during the transition period.

8. Advance Payment Invoice (Faktura Zaliczkowa)

An advance payment invoice is issued when a seller receives payment before delivering goods or services. Under Polish VAT law, the receipt of an advance payment triggers a VAT obligation at the moment the funds are received, and the seller must issue the invoice by the 15th of the month following receipt.

When the transaction is completed, the final invoice must reference all earlier advance payment invoices and reconcile the total amounts. AP teams should track advance invoices carefully to avoid double-counting when the final settlement invoice arrives.

Split payment rules apply to advances exceeding PLN 15,000 for goods and services listed in Annex 15 of the VAT Act. Understanding the Polish split payment mechanism and when it applies is essential for correctly processing these higher-value advance transactions.

9. Self-Billing Invoice (Samofakturowanie)

Under a self-billing arrangement, the buyer issues an invoice on the seller's behalf. This requires a prior written agreement between both parties that defines the scope and terms of the self-billing arrangement.

The buyer must file a ZAW-FA form with the Polish tax authorities to register the self-billing arrangement. Under KSeF, the buyer issues a structured invoice through the system on the seller's behalf, and both parties can access the document through their respective KSeF accounts. If you operate under a self-billing arrangement, ensure the ZAW-FA registration is current and that each invoice correctly identifies the arrangement.

10. Receipt (Paragon)

Receipts are B2C cash register documents issued at the point of sale. They continue to exist alongside KSeF and are not issued through the e-invoicing system.

If a customer requests a VAT invoice based on a receipt, the seller can issue one within the prescribed deadlines (generally by the 15th of the month following the request, provided the request is made within three months of the transaction). When processing reimbursements or expense claims, verify whether a proper VAT invoice has been obtained before booking a receipt-based business purchase.

Practical Summary

While the standard faktura VAT accounts for the vast majority of B2B transactions, AP teams processing Polish invoices may encounter any of these ten types depending on the supplier, the transaction structure, and the goods or services involved. Each type carries its own set of additional requirements and KSeF rules. Verifying that an invoice meets its type-specific obligations is a necessary step before booking it for VAT recovery or payment.

Currency, Language, and Numbering Rules

Polish VAT law permits invoices in any currency, but one rule catches many foreign AP teams off guard: the VAT amount must always be expressed in PLN (Polish Zloty), regardless of the transaction currency. An invoice denominated in EUR or USD that omits the PLN-equivalent VAT figure is technically non-compliant, and accepting it without flagging the issue can create problems during a tax audit.

When converting foreign currency amounts to PLN, the applicable rate is the average exchange rate published by the National Bank of Poland (NBP) on the last business day preceding the tax point (the date the tax obligation arises). Alternatively, the seller may use the rate published by the European Central Bank (ECB) for the same date. Verify which rate was applied and confirm it matches the correct reference date, since even small discrepancies can compound across high-volume invoice runs. AP teams handling invoices from multiple EU suppliers will find that each member state imposes its own currency and field-level rules — for example, Greece's VAT invoice requirements mandate similar mandatory field sets but use distinct terminology and the AADE myDATA reporting system instead of KSeF.

Language Requirements

There is no statutory requirement for Polish invoices to be issued in Polish. Foreign-language invoices are fully valid under the VAT Act, and bilingual invoices (Polish alongside a second language) are common in international trade. That said, two practical considerations matter for AP departments:

Audit translation requests. Under Article 287 of the Tax Ordinance, Polish tax authorities may request a certified Polish translation of any invoice during an audit. If your organization regularly processes Polish-language invoices, maintaining a reference glossary of standard field names (such as numer faktury for invoice number, data wystawienia for issue date, and kwota podatku for tax amount) reduces response time.
Field identification. Teams receiving invoices entirely in Polish should be able to locate and match the mandatory fields even without full translation. Familiarity with the standard Polish invoice vocabulary prevents data-entry errors and speeds up three-way matching.

For cross-border transactions, issuing bilingual invoices is recommended but not legally required.

Invoice Numbering Requirements

Poland's VAT Act requires every invoice number to be unique and sequential within the seller's numbering system. Continuity in the numbering sequence is strictly enforced. Gaps or out-of-order numbers in a supplier's invoice series are a known trigger for scrutiny from Polish tax authorities, as broken sequences can suggest unreported transactions or voided documents.

Sellers may organize their numbering using prefix or series systems. Common approaches include monthly prefixes (for example, FV/02/2026/001), departmental codes, or branch identifiers. From a receiver's perspective, recognizing the prefix pattern helps when reconciling invoices against purchase orders or payment schedules.

One additional layer applies under Poland's National e-Invoicing System (KSeF): each invoice processed through KSeF receives a system-generated identification number assigned by the platform, separate from the seller's own invoice number. Once KSeF becomes mandatory, every structured invoice will carry both numbers, and AP teams will need to reference the KSeF identifier for official correspondence with Polish tax authorities.

KSeF and Mandatory E-Invoicing by Invoice Type

Poland's Krajowy System e-Faktur (KSeF), or National E-Invoice System, establishes a centralized government platform for issuing, receiving, and storing structured e-invoices. Under the updated regulations, KSeF mandates that most B2B invoice transactions flow through the system in a standardized XML format, replacing the previous voluntary adoption period. For AP teams and finance professionals processing invoices from Polish suppliers, understanding which invoice types fall under Poland's mandatory KSeF e-invoicing system is essential for maintaining compliant workflows.

KSeF Status by Invoice Type

Not all of the 10 Polish invoice types carry the same KSeF obligations. The breakdown below reflects the rules in effect from 2026:

KSeF Category	Invoice Types	Notes
Mandatory through KSeF (2026)	Standard VAT invoices (faktura VAT), corrective invoices (faktura korygujaca), advance payment invoices (faktura zaliczkowa), margin invoices (faktura marza), self-billing invoices (samofakturowanie)	These must be issued and transmitted through KSeF for all domestic B2B transactions.
Optional / Transitional	Simplified invoices (faktura uproszczona) may remain outside KSeF through the end of 2026. RR invoices (faktura VAT RR) for agricultural purchases are optional in KSeF until at least April 2026.	Businesses should monitor legislative updates, as these exemptions have defined sunset dates.
Outside KSeF Scope	Pro forma invoices, receipts (cash register fiscal documents)	These are not tax invoices under the VAT Act and are not processed through KSeF.

Correction Notes and the February 2026 Cutoff

As covered in the invoice types section above, correction notes (nota korygujaca) were eliminated from the Polish VAT framework on February 1, 2026. All corrections must now flow through KSeF as corrective invoices issued by the seller. If your AP procedures still reference correction notes, update them to route all correction requests through the supplier's KSeF account.

Practical Implications for AP Receivers

Every invoice transmitted through KSeF receives a system-generated identification number assigned by the platform at the time of issuance. This KSeF identification number is separate from the seller's own invoice number and serves as a unique reference within the government system. AP teams should capture and store both the seller's invoice number and the KSeF identification number for each received invoice. Maintaining both references is critical for audit trails, as Polish tax authorities may request either identifier during compliance reviews.

For organizations based outside Poland that receive invoices from Polish suppliers, the shift to KSeF means incoming invoices will arrive in a structured XML format with the KSeF identification number included. Even if your own jurisdiction does not require e-invoicing, your systems and workflows should be prepared to parse and store invoices in this format. Coordinating with Polish suppliers on how they will deliver KSeF-compliant invoices, whether through direct system access, PDF renditions with embedded KSeF data, or integration via accounting platforms, will reduce friction during the transition.

One practical question for AP receivers: what if a Polish supplier sends an invoice outside KSeF for a transaction that required it? Exercise caution with non-KSeF invoices for transaction types listed as mandatory above. While the VAT deduction right is not automatically voided, the invoice may face scrutiny during audits, and your organization could be asked to verify the transaction through the KSeF platform.

Alongside KSeF compliance, record retention obligations apply to every Polish invoice your organization receives or issues.

Invoice Retention and Compliance Deadlines

Polish tax law requires businesses to retain all invoices for a minimum of 5 years from the end of the fiscal year in which the tax obligation arose. This applies regardless of invoice type. A standard VAT invoice issued in March 2024, for example, must be kept on file until the end of 2029 at the earliest.

The introduction of KSeF adds a secondary layer of archival. The government's KSeF platform stores e-invoices for 10 years from the date of issue, providing a longer-term backup accessible through the system. However, this extended archive does not replace or shorten the business's own 5-year retention obligation. Companies must still maintain their own records independently of KSeF, as the government archive serves as an additional reference rather than a substitute for internal compliance.

In practice, many Polish businesses and their foreign counterparts maintain records for 6 years as a buffer. This is particularly common when fiscal years and calendar years do not align perfectly, or when organizations want to account for potential audits that may reference overlapping tax periods. If you are comparing invoice retention periods across different jurisdictions, you will find that Poland's 5-year minimum falls within the typical European range, though the KSeF archive extends effective availability well beyond that.

For AP teams receiving invoices from Polish suppliers, the retention obligation applies equally to both issued and received invoices. Your organization must retain every Polish invoice it receives for the full 5-year period, stored in a way that preserves the document's integrity and allows retrieval upon request by Polish tax authorities. This includes paper invoices, PDF copies, and structured e-invoices received through KSeF.

With the retention timeline and obligations established, the final practical step for AP teams is building a systematic process to verify that each received Polish invoice meets all the applicable requirements before it enters your records.

Verification Checklist for Received Polish Invoices

Everything covered in the preceding sections comes together here. This checklist is written specifically for the recipient of a Polish invoice, not the issuer. Use it as a step-by-step reference each time you review a received invoice before approving it for payment.

1. Confirm all 11 mandatory fields are present. Cross-reference the invoice against the requirements of Article 106e of the VAT Act. Every standard VAT invoice must include the issue date, sequential number, seller and buyer NIP numbers, seller and buyer names and addresses, description of goods or services, quantity, net unit price, net amount, VAT rate, and gross amount.

2. Verify the supplier's NIP. The Numer Identyfikacji Podatkowej should be exactly 10 digits. For intra-EU transactions, it must carry the PL prefix (e.g., PL1234567890). An incorrect or missing NIP is one of the most common reasons for invoice rejection.

3. Check that the invoice number follows a sequential pattern. Polish VAT law requires each invoice to carry a unique number within a series that allows unambiguous identification. If a number appears duplicated or out of sequence relative to prior invoices from the same supplier, flag it for clarification.

4. Confirm the VAT rate matches the goods or services described. The standard rate is 23%. Reduced rates of 8% and 5% apply to specific categories (food products, medical supplies, books, among others). A 0% rate applies to qualifying intra-Community supplies and certain exports. If the rate does not align with what was delivered, request a corrective invoice before processing.

5. Verify the VAT amount is shown in PLN. Regardless of the transaction currency, Polish VAT law requires that the VAT amount be expressed in Polish zloty. If the invoice is denominated in EUR, USD, or another foreign currency, there must still be a PLN conversion of the VAT figure using the appropriate NBP exchange rate.

6. For corrective invoices: confirm the original invoice number and date are referenced. A valid corrective invoice (faktura korygujaca) must identify the original document it amends. If the reference to the original invoice number and issue date is missing, the corrective invoice is incomplete and should be returned to the supplier.

7. For advance payment invoices: verify the advance amount and check split payment applicability. Confirm that the advance payment invoice states the amount received and the related goods or services. For transactions exceeding PLN 15,000 that involve goods or services listed in Annex 15 to the VAT Act, the mandatory split payment mechanism applies. Look for the annotation "mechanizm podzielonej platnosci" on the invoice.

8. For simplified invoices: confirm the gross total is at or below the threshold. A simplified invoice is only valid when the total amount does not exceed PLN 450 (or EUR 100 for foreign-currency equivalents). If the gross amount is above this limit, the document must meet full invoice requirements instead.

9. Check for a KSeF identification number. Once mandatory e-invoicing through the Krajowy System e-Faktur takes effect, invoices that should have been issued through KSeF will carry a unique KSeF identification number. Verify its presence on invoices where KSeF submission is required, and confirm it against the KSeF platform if your organization has access.

10. Verify the invoice date falls within the permitted window. A VAT invoice must not be issued more than 60 days before the supply of goods or services takes place, and no later than the 15th day of the month following the month of delivery. If the issue date falls outside this range, the invoice may not be valid for VAT deduction purposes.

11. For invoices received in Polish, confirm that key data can be accurately extracted. Verify that amounts, NIP numbers, dates, and VAT rates can be mapped correctly to your internal records. If your organization processes Polish-language invoices regularly, maintain a reference glossary of standard field names (numer faktury, data wystawienia, kwota podatku) and a translation-ready process for audit requests under Article 287 of the Tax Ordinance.

Common Rejection Triggers

Even when an invoice appears complete at first glance, four issues account for the majority of rejections during AP review:

Missing or incorrect NIP on either the seller or buyer side
VAT amount not converted to or shown in PLN on foreign-currency invoices
Missing invoice number, or a number that does not allow unambiguous identification
Corrective invoices that fail to reference the original invoice number and date

Flagging these items early prevents downstream compliance problems and avoids delays in payment processing.

With these verification steps built into your AP workflow, you can process received Polish invoices with confidence that each document meets the requirements of the VAT Act before it enters your accounting system.

Key Takeaways for Processing Polish Invoices

Poland's VAT invoice framework is detailed and specific, but a few foundational points cover the majority of what AP teams and finance professionals encounter in daily processing.

Article 106e defines the baseline. Every standard Polish VAT invoice must include 11 mandatory fields, from sequential invoice number and issue date through to net amounts, applicable VAT rates, and gross totals. Poland applies four VAT rates (23%, 8%, 5%, and 0%), and the correct rate must match both the goods or services supplied and the invoice classification.

Ten distinct invoice types create real compliance variation. Beyond the standard faktura VAT, Poland recognizes nine additional types, each carrying its own supplementary requirements. Three deserve particular attention from AP teams:

RR invoices reverse the normal issuing relationship. The buyer, not the seller, creates the invoice when purchasing from flat-rate farmers. Receiving one of these from a Polish counterpart means the buyer bore responsibility for its accuracy at the point of creation.
Margin invoices show no separate VAT line item. The tax is embedded within the total price, which changes how you record and reconcile these documents.
Correction notes (noty korygujace) were eliminated from the Polish VAT system in February 2026. Any correction note dated after this cutoff is non-compliant and should be rejected.

The PLN rule is a frequent compliance pitfall. Regardless of the transaction currency, VAT amounts on every Polish invoice must be stated in Polish zloty (PLN). An invoice billed in EUR or USD that omits the PLN-denominated VAT figure fails Poland's tax invoice rules, even if all other fields are present and correct. AP teams processing cross-border invoices from Polish suppliers should flag this during initial review.

KSeF changes how you track invoices. Most Polish invoice types must now pass through the Krajowy System e-Faktur (KSeF). For AP workflows, this means each invoice carries two identifiers: the seller's own invoice number and the KSeF system identification number. Both should be captured and stored, as Polish tax authorities use the KSeF number as the primary reference during audits.

Retention spans a minimum of five years from the end of the fiscal year in which the tax obligation arose. Invoices processed through KSeF are archived by the government system for 10 years, but organizations remain responsible for maintaining their own accessible records for the statutory five-year window.

Practical next steps for AP teams: Incorporate the verification checklist from this article into your standard invoice processing workflow for Polish suppliers. If your organization is new to handling Poland VAT invoice requirements, begin with the mandatory fields under Article 106e and the three most common invoice types: standard (faktura VAT), corrective (faktura korygujaca), and advance payment (faktura zaliczkowa). Build familiarity with specialized types like RR, margin, and simplified invoices as you encounter them. This staged approach keeps onboarding manageable while ensuring compliance from the first invoice you process.