Ecuador Withholding Tax Invoice Requirements: AP Workflow Guide

When a supplier invoice lands in your AP queue in Ecuador, paying it triggers a tax obligation that many multinational teams only discover after a missed deadline. The buyer, acting as a retention agent, must issue an electronic withholding certificate (known as the comprobante de retención) when payment is made or when the amount is credited to the supplier's account, whichever occurs first. That certificate must be delivered to the supplier within five business days of the sales voucher being presented. Since November 2022, all withholding certificates must be issued in version ATS format, meaning the certificate data feeds directly into the Anexo Transaccional Simplificado (ATS) reporting annexes filed with Ecuador's tax authority, the Servicio de Rentas Internas (SRI).

These Ecuador withholding tax invoice requirements place the comprobante de retención squarely inside your invoice-to-payment-to-reporting cycle, not off to the side as a standalone tax exercise. The operational sequence runs like this:

1. Supplier invoice arrives and enters AP review.
2. Payment is made or the amount is credited to the supplier's account.
3. The buyer issues the electronic comprobante de retención in version ATS format.
4. The supplier receives the certificate within five business days of presenting the sales voucher.
5. Certificate data flows into ATS reporting for the corresponding tax period.

This workflow is governed by Ecuador's voucher regulation, the Reglamento de Comprobantes de Venta, Retención y Documentos Complementarios, and administered by the SRI. Every retention agent, whether a large domestic corporation or a foreign company with a local presence, follows the same sequence and the same deadlines.

Most English-language resources on Ecuador withholding certificate requirements stop at a rate table or fold the topic into a broader e-invoicing overview. This guide takes a different approach: it walks through the comprobante de retención as an AP workflow, step by step, from retention agent qualification through certificate issuance, delivery deadlines, version ATS reporting changes, and the March 2026 percentage updates that affect how much you withhold.

Who Qualifies as a Retention Agent in Ecuador

Not every taxpayer in Ecuador is required to withhold taxes from supplier payments. The Servicio de Rentas Internas (SRI) designates specific entities as retention agents (agentes de retención), and if your entity holds that designation, every qualifying supplier payment triggers a compliance obligation your AP team cannot ignore.

Retention agents fall into two broad categories:

Designated by law. Certain entity types are retention agents by default. This includes public sector entities, corporations and companies (sociedades), specific categories of exporters, and any entity that issues liquidaciones de compras (purchase settlement vouchers). If your organization is structured as a company operating in Ecuador, it almost certainly falls here.

Designated by SRI resolution. The SRI can also designate specific taxpayers as retention agents through administrative resolution, regardless of their legal structure. This sometimes catches entities that would not otherwise expect the obligation. Private individuals (personas naturales) are generally not retention agents unless the SRI has specifically designated them.

What Triggers the Obligation

The retention agent's duty to withhold and issue a certificate does not activate when a supplier sends an invoice or when a service is delivered. The triggering event is the payment or the accounting credit to the supplier, whichever comes first. This distinction matters for AP workflow design: the moment your team processes a payment or records a credit entry for a transaction subject to withholding, the clock starts on your obligation to calculate, deduct, and document.

In practice, this means your AP process must include a withholding checkpoint before payment release. When a supplier payment is processed for a transaction subject to withholding, your team must:

1. Identify whether the transaction type is subject to income tax withholding, VAT withholding, or both.
2. Calculate the correct withholding amount based on the applicable percentage for that payment category (services, goods purchases, professional fees, etc.) and the supplier's tax characteristics.
3. Deduct the withholding amount from the payment to the supplier.
4. Issue an electronic withholding certificate (comprobante de retención electrónico) to the supplier, documenting the amounts withheld.

Joint Liability Is the Real Risk

Getting this wrong carries direct financial consequences. If a retention agent applies an incorrect withholding percentage, fails to withhold entirely, or withholds but does not remit to the SRI, the agent becomes jointly liable for the unpaid tax. The liability does not shift to the supplier. Your entity absorbs it, plus any applicable interest and penalties.

For controllers overseeing multiple clients or subsidiaries, this means verifying retention agent status for each entity is a prerequisite to configuring payment workflows. An entity that was not previously designated can be added by SRI resolution at any time, so periodic verification against SRI records is advisable.

When and How to Issue the Comprobante de Retención

The withholding certificate workflow in Ecuador follows a strict sequence, and AP teams need to internalize each step to avoid compliance gaps. Missing a single checkpoint — particularly the five-business-day delivery deadline — creates problems that extend beyond your own books and into your supplier relationships.

The Issuance Sequence

The process moves through four stages:

1. The supplier presents a sales voucher. This is the triggering event. The voucher may be a factura (invoice), nota de venta (sales note), or liquidación de compras (purchase settlement). The moment this document reaches the buyer, the compliance clock starts.

2. The buyer makes payment or credits the amount. Your AP team processes the payment or records the payable against the supplier's account. The withholding obligation attaches at this point, but the deadline for delivering the certificate traces back to step one — not to the payment date.

3. The retention agent calculates and issues the electronic withholding certificate. Based on the applicable withholding percentages for income tax, VAT, or both, your team determines the amount to withhold and generates the comprobante de retención electrónico through the SRI's authorized electronic invoicing system.

4. The certificate is delivered to the supplier within five business days of the sales voucher presentation. This is non-negotiable. The supplier needs this document to claim the withheld amount as a tax credit.

The Five-Business-Day Deadline

This deadline causes more confusion than any other element of Ecuador's withholding workflow, because the clock starts from the date the supplier presents the sales voucher — not from the payment date.

Consider a concrete example: a supplier delivers an invoice on Monday. Your AP team schedules payment for Wednesday of the same week. The five business days run from Monday, not Wednesday. If your team treats the payment date as the starting point, you lose two days of runway without realizing it.

For AP departments that run weekly or biweekly payment cycles, this distinction is critical. You may receive an invoice days before payment is approved, and the delivery deadline is already counting down. Build your workflow to trigger certificate preparation at invoice receipt, not at payment execution.

What the Certificate Must Contain

Every comprobante de retención must include the following data points:

• Retention agent identification — RUC, business name, and address of the entity performing the withholding
• Supplier identification — RUC or RISE number, name, and address of the party subject to withholding
• Tax base — the amount on which the withholding is calculated
• Withholding percentage applied — the specific rate used for the transaction
• Amount withheld — the resulting figure after applying the percentage to the tax base
• Type of tax withheld — whether the withholding applies to income tax (impuesto a la renta), VAT (IVA), or both
• SRI authorization number — the unique identifier assigned by the Servicio de Rentas Internas confirming the document's validity

Omitting or misreporting any of these fields can trigger rejection during SRI validation, forcing a void-and-reissue cycle that eats further into your deadline.

One Certificate Per Transaction

A single withholding certificate covers the withholdings applied to a single invoice. You cannot batch unrelated supplier invoices into one certificate. The exception is narrow: if multiple invoices from the same supplier correspond to the same payment event, they can be consolidated into one comprobante de retención.

Consequences of Missing the Deadline

Failing to deliver the withholding certificate within five business days creates two distinct problems:

For the supplier: The withheld amount cannot be claimed as a tax credit until the situation is corrected. Suppliers who repeatedly face delayed certificates will escalate or reconsider terms.

For the retention agent: The SRI can impose administrative penalties for non-compliance with issuance deadlines. Repeated violations increase scrutiny on your filing history and may trigger audits.

Correcting Errors

If a withholding certificate contains incorrect data — a wrong percentage, misidentified supplier, or incorrect tax base — it can be voided and reissued. However, electronic document cancellation in Ecuador follows specific procedural rules. The original certificate must be formally annulled through the SRI system before a corrected version is generated. For a full breakdown of this process, refer to the rules for cancelling electronic vouchers in Ecuador. Initiating a correction promptly matters, because the reissued certificate still needs to reach the supplier in a timeframe that preserves their ability to claim the tax credit.

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How Version ATS Changes Withholding Certificate Reporting

The term "version ATS" refers to a structured electronic format for withholding certificates whose fields align directly with the Anexo Transaccional Simplificado (ATS) — the simplified transactional annex that every taxpayer must file with the SRI. The ATS details purchases, sales, and withholdings for each tax period, and it serves as the transactional backbone behind monthly declarations.

Resolution NAC-DGERCGC22-00000024 required all taxpayers designated as retention agents to adopt electronic withholding certificates in the version ATS format by November 29, 2022. This was not optional. Any entity classified as a retention agent — whether by designation, revenue threshold, or taxpayer category — had to transition its comprobantes de retención to this structured electronic format by that deadline.

The operational payoff is significant. When your organization issues withholding certificates in version ATS format, the data contained in those electronic documents does not need to be re-registered in the purchases and sales modules of the ATS annex for the same fields. Before this transition, compliance teams manually entered withholding data into the certificate and then duplicated much of that information when preparing the ATS filing. Version ATS eliminates that redundancy — the certificate itself feeds the annex directly. This matters because retention agents file Formulario 103 monthly to declare and remit the income tax withheld from suppliers, and the ATS annex provides the transactional detail behind those Formulario 103 totals. With version ATS certificates flowing data directly into the annex, the reconciliation path from individual withholding certificates to monthly declarations becomes more traceable and less prone to transcription errors.

Withholding certificates sit within Ecuador's electronic invoicing framework as one of several authorized electronic document types. The SRI's electronic voucher system also processes facturas, notas de crédito, notas de débito, guías de remisión, and liquidaciones de compras. The scale of this ecosystem is substantial: nearly three million taxpayers are registered in the system, which processes over eight million authorized electronic documents — including withholding certificates — on a typical business day, according to SRI's real-time electronic voucher dashboard. For AP and compliance teams, this means your version ATS withholding certificates are validated against the same infrastructure that handles every other electronic tax document in the country.

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March 2026 Withholding Percentage Updates

The SRI's Resolution NAC-DGERCGC26-00000009 established new withholding percentages effective March 1, 2026, updating the rates that retention agents must apply when withholding income tax on supplier payments. For AP teams processing invoices in Ecuador, this resolution requires immediate attention — certificates issued with outdated rates for transactions on or after March 1 are non-compliant, regardless of when the invoice was received.

What changed operationally: Every withholding certificate (comprobante de retención) generated for payments from March 1, 2026 onward must reflect the updated percentage tables. This means your ERP or accounting system's withholding configuration needs to match the new rates exactly. A certificate that applies the old percentages to a March 2026 transaction will not satisfy SRI requirements, even if the format and timing are otherwise correct.

The transitional grace period — now expired. Recognizing that retention agents needed time to reconfigure their systems, the SRI announced a transitional measure: withholding certificates for transactions occurring during the first half of March 2026 (March 1 through 15) could be issued as late as March 31, 2026 without sanctions. That window has closed. All certificates must now be issued with the correct new rates and within the standard five-business-day delivery window.

Practical steps for AP teams:

• Verify your withholding percentage tables. Confirm that every applicable rate in your system matches Resolution NAC-DGERCGC26-00000009. Cross-check against the SRI's published tables rather than relying on secondhand summaries.
• Audit certificates issued in March 2026. Review any comprobantes de retención generated during the first two weeks of March. If any were issued using prior rates, confirm they were corrected or reissued before the March 31 grace deadline.
• Retain grace-period documentation. For certificates issued during the transitional window, keep records showing the original issuance date, the corrected certificate (if applicable), and any SRI communications referencing the grace period. This documentation protects you during audits.
• Update internal process checklists. Add a rate-verification step to your AP workflow so that future SRI rate changes are caught and applied before the first affected certificate is issued.

AP teams operating across multiple withholding jurisdictions can compare Ecuador's workflow with Thailand's withholding tax certificate process, which follows a different issuance timeline and format but imposes similar retention agent obligations and periodic rate adjustments.