Confirm the registered entity and return period
Begin by confirming the legal entity, GST number, taxable period, filing frequency and accounting basis in myIR or the permanent file. The accounting system must use the same period and basis. This sounds basic, but return errors frequently begin with the wrong dates, a changed filing frequency or a GST setting that was never updated after registration. Record the statutory due date and an earlier internal completion date.
Inland Revenue says GST returns are generally due on the 28th of the month after the taxable period. Periods ending 31 March are generally due 7 May, and periods ending 30 November are generally due 15 January. Returns must be filed for every taxable period, even when there is no activity. Check the current key dates before finalising because weekends, public holidays and administrative changes can affect the practical payment date.
Complete the bookkeeping before reviewing GST
Import or obtain bank statements through the period end and reconcile every business bank and credit-card account. Enter missing sales invoices, bills, credit notes, expense claims, payroll journals, loan transactions and asset purchases. Review duplicate transactions, deleted entries, unreconciled statement lines and amounts sitting in suspense. A GST report generated from incomplete bookkeeping may be internally consistent but still wrong because the underlying transactions are missing.
Reconcile receivables and payables where the GST basis makes those balances relevant. Confirm that sales systems, e-commerce platforms and payment gateways have been posted completely and without duplication. For cash businesses, compare deposits with sales records. For businesses using multiple systems, document the control totals between the source system and Xero or the general ledger.
Review tax coding and high-risk transactions
Scan the GST audit report for unusual tax rates, negative GST, large manual journals and transactions coded directly to GST control accounts. Review overseas sales, imported services, zero-rated supplies, exempt income, property transactions, asset purchases and disposals, entertainment, private use, insurance settlements, bad debts and prior-period adjustments. These areas may require New Zealand tax judgement and should be listed for the responsible adviser.
Do not assume the default tax code is correct because it was used in earlier periods. Supplier and bank rules can create systematic errors. Select a sample of material transactions and compare the tax code with the invoice and the nature of the supply. For expenses, confirm that a valid taxable supply information record or other acceptable evidence is retained where required. Separate missing-document items from technical-treatment questions.
Reconcile the GST return to the ledger
The GST return should tie to the GST control accounts after considering opening balances, payments, refunds and adjustments. Prepare a reconciliation showing the opening GST payable or receivable, GST generated by the current return, payments or refunds, journals and the closing ledger balance. Investigate any difference rather than posting a balancing journal without explanation. A clear reconciliation allows the reviewer to distinguish timing from error.
Compare taxable sales with revenue reports and review the effective GST rate. Large changes from prior periods should be explained by sales mix, timing, zero-rated supplies, capital purchases or corrections. If Xero is used, retain the GST return, GST audit report and any exception reports. Finalise or lock the return only after the local reviewer has approved the treatment and the filing responsibility is clear.
Create a complete filing and payment record
Before filing, provide the reviewer with the draft return, reconciliation, significant transactions, adjustments, missing records and open technical questions. After filing, save the filed confirmation, payment details and final return pack. Post the final GST journal if the accounting process requires one, and confirm that the ledger balance agrees to the filed obligation and subsequent payment or refund.
Use the completion process to improve the next period. Update bank rules, supplier defaults and coding guidance for confirmed errors. Add recurring documents to the collection checklist and record decisions in the permanent file. A strong GST process should reduce exceptions over time while preserving professional review for transactions that genuinely require judgement.