In New Zealand, use AI for the checking around a GST return, not the filing: read supplier documents, flag missing taxable supply information, compare each box with the ledger and prior periods, and keep a deadline calendar. Returns fall due on the 28th after each period, with 7 May and 15 January exceptions; a person signs off.
Two local facts change the advice. Inland Revenue (IRD) replaced the tax invoice with "taxable supply information" from 1 April 2023, so assistants trained on older material may quote rules that no longer apply. And Xero's plan names, prices and AI features differ by region, so a guide written for another country can point you at the wrong plan.
The walk-through follows one two-monthly return for a six-person marketing agency, from supplier documents to a corrected GST101A. Amounts are in New Zealand dollars (NZD) and every business figure is an illustration. Thresholds, dates and penalties come from IRD's GST guide (IR375, March 2026) and its filing pages, read in November 2026.
AI never files, signs or decides tax treatment in any of this. IRD's guide says the registered person is personally responsible for the accuracy of the information on the return, and that does not change when software or an assistant prepared the numbers.
What IRD's guide says, and what to automate
| Rule | What IRD says | Where AI or software helps |
|---|---|---|
| Registration | Required if turnover was at least NZD 60,000 in the last 12 months or is expected to be at least that in the next 12 | A rolling 12-month turnover check on the ledger |
| Rate and fraction | GST is usually 15%; the GST in a GST-inclusive price is the price multiplied by 3 and divided by 23 | A spreadsheet formula, never a chat answer |
| Filing frequency | Monthly if sales exceed NZD 24 million in any 12 months; two-monthly if under NZD 24 million; six-monthly if under NZD 500,000. Periods must align with your balance date | A calendar built from the balance date |
| Due date | 28th of the month after the period ends; 7 May for periods ending 31 March; 15 January for periods ending 30 November; a weekend or public holiday moves it to the next working day. Payment is due the same day | Calendar reminders, set a week early |
| Nil returns and extensions | A return is required for every period even if nil, and you cannot get an extension of time | A "no return filed yet" alert for every period |
| How to file | In myIR, through accounting software with a pre-populated return, or on paper | Software that pre-fills the return, checked by a person |
| Accounting basis | Payments, invoice or hybrid; IRD puts you on the invoice basis if you do not choose | A check that the software's setting matches the basis registered |
| Records | Keep business records for 7 years, including taxable supply information for claims | Document capture with a completeness check |
| Late filing penalty | NZD 50 per return on the payments basis; NZD 250 per return on the invoice or hybrid basis | The reminder in row four is the cheapest control |
Most of that table is arithmetic and dates, which a spreadsheet does better than a chat assistant. AI earns its place in the reading, the flagging and the drafting.
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Buy nowA deadline calendar for a March balance date
For a two-monthly filer with a 31 March balance date, IRD's guide gives the taxable periods as April to May, June to July, August to September, October to November, December to January and February to March. Apply the due-date rule to each and the year looks like this:
| Taxable period | Period ends | Return and payment due |
|---|---|---|
| April to May | 31 May | 28 June |
| June to July | 31 July | 28 August |
| August to September | 30 September | 28 October |
| October to November | 30 November | 15 January |
| December to January | 31 January | 28 February |
| February to March | 31 March | 7 May |
Two of the six dates break the 28th pattern, and a calendar built from memory or from an assistant's guess will miss them. A weekend or public holiday moves any date to the next working day, so check each year's calendar day by day. Build the table in a spreadsheet from the balance date and filing frequency, ask an assistant only to write the formula, and compare the output with IRD's filing page before you share it with a client.
Employers carry two more dates in the same calendar. IRD says employment information must be filed within 2 working days of each payday when filing electronically, and that deductions are paid by the 20th of the following month when gross annual PAYE and employer superannuation contribution tax is under NZD 500,000, or twice a month above that. Income tax and provisional tax dates depend on balance date, and IRD publishes a yearly key dates calendar for them, so copy those from IRD rather than from a tool.
Checking supplier documents against taxable supply information
Since 1 April 2023 there is no tax invoice rule. IRD's guide sets out the minimum information buyers and sellers must keep, in three tiers by the value of the supply, and it can be spread across invoices, contracts and bank statements. That is a good job for document capture plus a rule list:
| Item to hold | NZD 200 or less | Over NZD 200, up to NZD 1,000 | Over NZD 1,000 |
|---|---|---|---|
| Seller's name or trade name | Yes | Yes | Yes |
| Seller's GST number | No | Yes | Yes |
| Date of invoice, or time of supply if no invoice | Yes | Yes | Yes |
| Description of the goods or services | Yes | Yes | Yes |
| Amount | The consideration | GST-exclusive, GST and GST-inclusive amounts, or the GST-inclusive amount with a statement that GST is included at the standard rate | Same as the middle column |
| Buyer's details | No | No | If the buyer is GST registered: name, and one of address, phone, email, trading name or business number or website |
Turn the table into five rules for whichever tool reads the documents. A bill over NZD 200 with no seller GST number is incomplete. A bill over NZD 1,000 without your business's details is incomplete. A GST amount that is not three twenty-thirds of the GST-inclusive total is wrong or covers mixed supplies. A document without a date needs the date of supply from another record. And any bill that fails goes to a queue for the client, not to the return. One caution: because tax invoices were the rule until April 2023, many guides and many models still talk about them and about older value limits. Check any assistant's claim against IR375 rather than arguing with it.
A two-monthly return, drafted straight from the ledger
The agency's August to September return is prepared from Xero's GST report without review. IRD's GST101A works like this: Box 5 is total sales and income including GST, Box 6 the zero-rated part, Box 7 the difference, Box 8 is Box 7 multiplied by 3 and divided by 23, Box 11 is total purchases and expenses including GST, and Box 12 is Box 11 multiplied by 3 and divided by 23. Box 10 is the GST collected, Box 14 the GST credit, and Box 15 the difference. The draft reads:
| Box | What it holds | Draft from the ledger (NZD) |
|---|---|---|
| 5 | Total sales and income, including GST | 138,000.00 |
| 6 | Zero-rated supplies in Box 5 | 2,760.00 |
| 7 | Box 5 minus Box 6 | 135,240.00 |
| 8 | Box 7 × 3 ÷ 23 | 17,640.00 |
| 9 | Adjustments | 0.00 |
| 10 | GST collected (Box 8 plus Box 9) | 17,640.00 |
| 11 | Total purchases and expenses, including GST | 71,300.00 |
| 12 | Box 11 × 3 ÷ 23 | 9,300.00 |
| 13 and 14 | Credit adjustments; total GST credit | 0.00; 9,300.00 |
| 15 | GST to pay (Box 10 minus Box 14) | 8,340.00 |
Every box is internally consistent, which is exactly why the draft looks fine. The errors sit in how individual ledger lines were coded, and only a line-level review sees them.
The prompt that reads the GST detail
Export the period's GST detail with contact names replaced by codes and keep the amounts and tax codes. Paste it into an assistant on a plan whose data terms you have accepted, and never include IRD numbers; IRD's guide says a GST number may be the same as the IRD number. Anonymising before you paste is covered in its own tutorial.
You are reviewing the GST detail for one two-monthly period for a
small business registered for GST on the invoice basis. Columns:
line, account, tax_code, amount_incl_gst, customer_location,
supplier_gst_number_present (Y/N).
Flag these only, quoting the line number:
1. Any expense coded with GST where the account is bank fees, loan
interest, wages or owner drawings (IRD lists these as items GST
cannot be claimed on).
2. Any sale coded zero-rated where customer_location is NZ.
3. Any entertainment expense, so I can check the Box 9 adjustment.
4. Any bill over 200 where supplier_gst_number_present is N.
Do not total anything and do not tell me what the tax rule is; say
only why the line was flagged.
1, Retainer fees, 15%, 6900.00, NZ, -
2, Project fees, ZERO-RATED, 2760.00, NZ, -
3, Software subscriptions, 15%, 345.00, -, Y
4, Bank fees, 15%, 230.00, -, Y
5, Loan interest, 15%, 1150.00, -, Y
6, Telecommunications, 15%, 575.00, -, Y
7, Client entertainment, 15%, 230.00, -, Y
8, Printing, 15%, 460.00, -, NAn illustrative result:
| Line | Why flagged | Effect on the draft |
|---|---|---|
| 2 | Zero-rated sale to a customer in NZ | NZD 360.00 of GST not charged (2,760 × 3 ÷ 23) |
| 4 | GST coded on bank fees | NZD 30.00 credit claimed that IRD says is not available |
| 5 | GST coded on loan interest | NZD 150.00 credit claimed that is not available |
| 7 | Entertainment expense | Check the Box 9 adjustment; see below |
| 8 | Bill over NZD 200 with no seller GST number | Taxable supply information incomplete; NZD 60.00 of credit (460 × 3 ÷ 23) is at risk until the supplier's GST number is on file |
The reviewed return, and what the assistant got wrong
The accountant works through the five flags. Line 2 is a project fee to a customer in NZ, and IRD's guide says zero-rated supplies are most likely for exporters: exported goods, sales of going concerns and some land sales. The agency has no such basis, so the invoice was coded wrongly and carries GST. Lines 4 and 5 are bank fees and loan interest, both on IRD's list of items you cannot claim GST on, so they come out of the GST credit. Line 8's supplier sends its GST number the next day and the bill stays in. Line 7, the client lunch, stays in Box 11 in full, because IRD's guide treats the entertainment adjustment as a separate step: for a NZD 230 lunch it works out the non-deductible half of the GST-exclusive cost (NZD 100), multiplies by 15% and gets NZD 15.00 for the IR372 sheet and Box 9. The guide gives the timing, so confirm which return carries it; in this example it falls in a different period and Box 9 stays at zero.
| Box | Draft (NZD) | Reviewed (NZD) | Reason |
|---|---|---|---|
| 6 | 2,760.00 | 0.00 | Sale to an NZ customer is not zero-rated |
| 7 | 135,240.00 | 138,000.00 | Box 5 minus Box 6 |
| 8 | 17,640.00 | 18,000.00 | 138,000 × 3 ÷ 23 |
| 10 | 17,640.00 | 18,000.00 | No adjustments this period |
| 11 | 71,300.00 | 69,920.00 | Remove bank fees 230 and loan interest 1,150 |
| 12 and 14 | 9,300.00 | 9,120.00 | 69,920 × 3 ÷ 23 |
| 15 | 8,340.00 to pay | 8,880.00 to pay | The draft understated the payment by 540.00 |
The 540.00 is 360.00 of GST not charged plus 180.00 of credit wrongly claimed. Under IRD's guide an error with a total discrepancy of NZD 1,000 or less can be corrected in the return for the period after you find it, so a missed 540.00 would not have been fatal. It would still have meant a wrong return with the agency's name on it, and the payment is due the same day as the return.
The assistant also made two mistakes in its first draft of the flag notes, and both are typical. It wrote that only half the GST on the entertainment line is claimable, which is wrong: the full credit is claimed and the adjustment comes later. And it said a tax invoice is required for purchases, which is the wording from before April 2023; the March 2026 guide asks for taxable supply information instead. The remedy is the one the prompt already uses: ask it why a line was flagged, not what the law says, and take the rule from IR375 yourself.
Xero plans, JAX and where they fit
Xero's New Zealand pricing page lists four plans in NZD excluding GST, each with an introductory discount for the first three months that I have left out. Plan names and prices differ on Xero's pages for other regions, so use this one for a New Zealand business.
| Plan | Regular price a month (NZD, excl. GST) | Bills and invoices | Document capture | Auto-categorising and matching |
|---|---|---|---|---|
| Ignite | 37 | 20 invoices and 5 bills | Basic extraction (labelled beta) | Auto-reconcile an optional add-on, NZD 8.00 a month |
| Grow | 89 | No limit stated, with automated bill entry | Basic extraction (labelled beta) | Included: JAX categorises and matches high-confidence bank transactions |
| Comprehensive | 117 | No limit stated, with automated bill entry | Smart document capture | Included |
| Ultimate | 135 | No limit stated, with automated bill entry | Smart document capture | Included |
Every plan lists tracking and filing GST returns. Three details matter for the workflow above. First, Ignite's limit of five bills means a business with a dozen supplier bills a month will outgrow it before GST day. Second, the depth of document capture differs by plan: Ignite and Grow get basic extraction, still labelled beta, while Comprehensive and Ultimate include smart document capture. The document checks earlier in this tutorial depend on extraction reading the supplier's GST number and the GST amount, so test it on your own documents. Third, "JAX" covers two things on Xero's pages: auto-categorising and matching high-confidence bank transactions, which sits in the plan table above, and JAX chat.
Xero's JAX page says JAX chat is available to all subscribers and users, that there is currently no extra charge, and that Xero reserves the right to change the terms and the price. It also says JAX only acts when you open it and ask, follows each user's permissions, and does not use your data to train the language models it relies on. That is useful for a question such as "show GST collected for the last two months", and the answer then needs checking against the GST report. It does not file or approve a return. Xero JAX bank reconciliation, set up and checked covers the matching feature in more detail, and the five-stage workflow from client upload to partner review shows where a GST review sits in a monthly close.
IRD letters, and errors found after filing
An assistant can turn an IRD letter into a table: what IRD asks, by when, which documents and who acts. Remove the IRD number, names and addresses first, because the identifiers are the sensitive part and the assistant does not need them. The usual defect is a misread date or a confusion between "by" and "within", so the person who owns the response reads the original. IRD's guide says the best way to contact it is a message in myIR, which also keeps the reply on the record. Whether it is safe for an accountant to use ChatGPT with client data covers the plan and settings question behind that.
If an error surfaces after filing, IRD's guide offers several routes, and the size of the discrepancy decides which. An error with a total discrepancy of NZD 1,000 or less can be corrected in the return for the period after you find it. A second route allows a correction in that next period if the discrepancy is no more than the lower of NZD 10,000 and 2% of the GST collected, and the purpose is not to delay payment. A third allows an unclaimed credit to be included later within 2 years in certain cases. Amending the return in myIR is another way, and changing a tax position you chose on purpose goes through IRD's disputes process, with a notice of proposed adjustment (IR770) due no later than 4 months after the return's due date. With that many branches, the sensible rule is to write down the amount, the cause and the period before choosing, and to ask the accountant.
A short example. An error of NZD 380 found in the next period fits the first route. An error of NZD 4,800 found in a return that collected NZD 60,000 of GST fails the second route, because 2% of NZD 60,000 is NZD 1,200, which is lower than NZD 10,000 and below the error. That one needs a different route, probably an amended return, and a conversation first.
What stays with the accountant
- Filing and signing. The person responsible reviews the return and files it in myIR or through connected software.
- Deciding tax treatment. Whether a supply is zero-rated, exempt or taxable, and how to apportion private use, is a judgement for the accountant working from IRD's guidance.
- Quoting rules and dates. Rates, thresholds, due dates and penalties come from IRD pages and are re-checked each year, not recalled by a model.
- Identifiers. IRD numbers, GST numbers, bank details and myIR credentials stay out of every chat tool.
Questions NZ businesses and accountants ask about AI and GST
Can AI file my GST return with IRD?
AI can prepare checks and drafts, but filing happens in myIR or through accounting software that connects to IRD, and the person filing is responsible for the figures. Xero lists tracking and filing GST returns on every New Zealand plan. Treat any AI step as review support and approve the return yourself.
When is my GST return due?
By the 28th of the month after your taxable period ends, except 7 May for periods ending 31 March and 15 January for periods ending 30 November. A date that falls on a weekend or public holiday moves to the next working day, and IRD says you cannot get an extension of time to file.
Does Xero JAX do my GST?
JAX chat answers questions from your Xero data and public information, is available to all subscribers at no extra charge for now, and only acts when you ask. Auto-categorising and matching bank transactions is a separate feature that depends on plan. Neither files or approves a return, so check every figure against the GST report.
Do I still need tax invoices?
IRD replaced the tax invoice requirement with taxable supply information from 1 April 2023. What you keep depends on the amount: NZD 200 or less, over NZD 200 up to NZD 1,000, and over NZD 1,000. An older guide, or an assistant trained on one, may still quote the old rules.
What if I find an error after filing?
IRD's GST guide lets an error with a total discrepancy of NZD 1,000 or less be corrected in the return for the period after you find it, sets other rules for larger amounts, and also allows an amended return in myIR. Ask your accountant which route fits the size and cause.
Further reads
- AI Bookkeeping in Canada: GST/HST Coding and Remittance Checks — The same return-checking idea for another sales tax.
- AI Accounting in Singapore: GST, ACRA Filings and Software Choices — Another country's GST return, with the same review method.
- Accountants AI Risk Checklist: Error Points, Each With a Named Check — Error points in an AI-assisted practice, each with a named check.
- AI Tools and AI Development: The Complete 2026 Guide — the AI hub, including every tutorial in the AI-for-business series.
Sources: Inland Revenue's GST guide IR375 (March 2026) and its pages on filing GST, GST filing frequency, payday filing and paying deductions; Xero's New Zealand pricing and JAX pages, all read in November 2026.