IR330C Form Explained: NZ Contractor Tax Notification

The IR330C is Inland Revenue's official form titled Tax rate notification for contractors. A contractor who receives schedular payments completes it to tell the payer which withholding tax rate to deduct from those payments. It is the document that sets the rate, so it matters to two people at once: the contractor declaring the rate, and the business that has to apply it.

The fact most people get wrong is where the form ends up. A completed IR330C goes to the payer, the person or business making the payments, and stays in their records. It is not sent to Inland Revenue. The payer uses it to work out the right deduction, then reports the tax it has withheld separately.

There is one more thing to know up front: what happens when the form is missing. If a payer does not hold a valid IR330C for a contractor, schedular payments are generally taxed at the 45% no-notification rate, or 20% for a non-resident company. Those rates are deliberately high, which is the practical reason the form gets completed and handed over promptly.

That is the IR330C form explained at its core: a withholding rate the contractor declares and the payer applies, kept in the payer's records and never sent to Inland Revenue.

Who Needs to Complete an IR330C

The IR330C applies to anyone who receives schedular payments: payments for certain types of contract work where tax is deducted at the source rather than left for the contractor to settle entirely at year end. If an engagement produces schedular payments, the contractor completes an IR330C; if it does not, the form has no role.

Schedular-payment payees are not only sole-trader individuals. A payee can be an individual, a partnership, a trust, or a company, which is why a contractor file might hold an IR330C for a one-person trade business and another for an incorporated contractor.

The clearest way to recognise whether the form applies is by the type of work. Inland Revenue's list of schedular-payment work includes labour-hire contractors, builders engaged through a labour-hire arrangement, company directors receiving directors' fees, real-estate agents, commercial cleaners, freelance journalists, insurance agents, and primary-industry labour contractors. It also covers non-resident contractors, entertainers, and sportspeople working in New Zealand. If a contractor's work sits in one of these categories, an IR330C belongs in the file.

For a finance or payroll team onboarding a new contractor or vendor, the question to settle early is simple: does this engagement produce schedular payments? That single answer decides whether you need a completed IR330C on file before the first payment goes out, and it is worth confirming at setup rather than discovering at payment time.

How the Withholding Tax Rate Choice Works

The IR330C does not assign a rate automatically. The contractor sets it, and there are three routes to the number that ends up on the form.

The first is the standard rate. The form includes a rate flowchart that points each type of schedular-payment work to a standard withholding rate, so a contractor who follows the flowchart for their activity lands on the rate Inland Revenue expects for that work. The second is a tailored rate, sometimes called a special rate: a contractor applies to Inland Revenue, which sets a rate based on their circumstances, useful when the standard rate would over- or under-deduct against their actual tax position. The third is to choose their own rate.

A self-chosen rate is not unlimited. According to Inland Revenue's guidance on declaring your schedular payment tax rate, a contractor who chooses their own schedular-payment tax rate must use a rate of at least 10%, or at least 15% if they are a non-resident on a temporary work or entry visa, and gives the completed form to the person who pays them. The floor stops a contractor from declaring a rate so low that almost nothing is deducted during the year.

The rate matters because it sets how much tax comes out of each payment. A higher rate deducts more as the contractor goes, leaving less owing (or a refund due) at year end; a lower rate keeps more cash in hand through the year but raises the chance of a tax bill when the return is filed. Which rate is right depends on a contractor's wider income and deductions, and Inland Revenue is the authority on that decision. The form's job is only to record the choice clearly so the payer can apply it.

The Fields That Matter on the Form

Most of the IR330C is straightforward identification, but a handful of fields decide the withholding outcome. Get these right and the form is valid; leave one blank and it may not be.

The fields that carry weight are the contractor's full name, their IRD number, the schedular-payment activity number for the type of work, the WT tax code, and the chosen tax rate. The name and IRD number tie the form to the right taxpayer. The remaining three set the deduction.

The activity number identifies the type of schedular-payment work, and it is the field most likely to trip up someone completing the form for the first time. It ties the work to the standard rate, so an incorrect activity number can point to the wrong rate before the contractor has even reached the rate field. The number comes from Inland Revenue's list of schedular-payment activities, matched to the work actually being done.

The WT tax code is what marks this as schedular-payment income. WT is the code that applies to schedular payments, and it is the reason contractors use the IR330C rather than the IR330. The IR330 is the Tax code declaration for salary and wage earners on PAYE; the IR330C is the Tax rate notification for contractors on schedular payments. They look similar and are easily confused, but a contractor on schedular payments needs the IR330C.

One obligation outlasts the moment the form is signed. The IR330C is a point-in-time declaration, not a permanent setting: if the contractor's tax code or chosen rate changes, they must tell the payer and supply a fresh IR330C. The payer keeps applying the rate on the most recent valid form until a new one arrives.

For the finance reader checking a form that has just come in, the test is completeness. A form missing the IRD number, the activity number, or the rate is not a valid notification, even if every other line is filled in, and an invalid notification carries the same consequence as no form at all.

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What the Payer Does With the Completed Form

So where does the completed IR330C form go? The contractor gives it to the payer, and it stays there. It lives in that contractor's vendor or supplier file alongside their other onboarding records. It is not posted or uploaded to Inland Revenue. This is the step the contractor-side guides tend to skip, and it is where the form does its real work.

Once on file, the form is the documentary basis for the rate the payer deducts. Every withholding taken from that contractor's invoices and schedular payments traces back to the rate declared on their IR330C. The form is what turns a number on a tax return into a number the payer can defend: this is the rate, here is the form the contractor signed to declare it.

That is why finance treats the IR330C as document control rather than paperwork. At payment time, the form on file is the evidence supporting the deduction. At reporting time, it is the basis for the figures the payer files. If the form is incomplete, missing, or out of date, the deduction loses its footing, which is the practical reason the form has to be complete when it arrives and kept current as the contractor's details change.

The form itself is only the first step on the payer's side. Validating it, applying the right rate, and processing the contractor's invoice is a fuller procedure, covered in detail in our guide to how an AP team checks the IR330C before paying a contractor invoice. For the purpose of understanding the form, the key point is narrower: the completed IR330C is the record that authorises the rate, and it belongs in the contractor's file from the first payment onward.

What Happens Without a Valid IR330C

The high default rates are the reason the form gets completed at all. Where a payer does not hold a valid IR330C for a contractor, schedular payments are generally taxed at the 45% no-notification rate; the one common exception is a non-resident company, deducted at 20%. A form that is incomplete counts the same as one that is absent, since an IR330C missing its IRD number, activity number, or declared rate is not a valid notification, and the payer falls back to the default as if no form existed.

The consequence lands on both sides. For the contractor, 45% is almost always more than their actual rate would have been, so the missing form means a heavier deduction through the year and a wait until the return is filed to reconcile the over-deduction and recover anything overpaid. For the payer, applying the correct default is a compliance obligation, not a choice: when no valid notification is held, the higher rate is the rate that must be deducted.

The takeaway is practical. A complete IR330C on file is what moves a contractor off the 45% default and onto their declared rate. Chasing the form before the first payment, rather than after, is what keeps both sides out of the no-notification position.

How the IR330C Connects to Contractor Tax Reporting

The withholding the IR330C sets does not end when the deduction is made. The payer has to account for that tax to Inland Revenue, which is the step that closes the loop between the form on file and the contractor's tax record. The mechanics of that filing, including how the deduction data is assembled and submitted, sit in our guide to reporting contractor deductions through the Employment Information return.

There is one adjacent fact contractors often need around the same time. Schedular-payment income counts toward the NZD 60,000 GST-registration threshold, measured on income before expenses, or where GST is added to the contractor's prices. As schedular-payment work grows, that threshold is the point at which GST registration moves from optional to required, and it is worth tracking alongside the withholding rate rather than treating the two as unrelated.

It helps to keep the IR330C in its lane. The form is the rate-setting document: it records the withholding rate and nothing more. Validating that rate, applying it to each contractor invoice, deducting correctly, and meeting the wider schedular-payment obligations is a broader process, set out in the wider schedular payments contractor withholding workflow. Read the form as the input to that workflow, not the workflow itself, and its role stays clear: declare the rate, hand it to the payer, keep it current, and let the deductions and reporting follow from there.