MyGST

Making GST Simple for NZ Small Business

New Zealand's GST system is straightforward compared to VAT regimes in other countries, but the compliance workflow — reconciling transactions, categorising income and expenses, producing the BAS-equivalent form — is still time-consuming for non-accountants.

Transaction Import

MyGST connects to bank accounts via the Plaid API for automated transaction sync, or accepts CSV exports from all major NZ banks. A rule engine automatically categorises common transaction types (subscriptions, fuel, utilities) and flags ambiguous ones for manual review.

GST Calculation Engine

The calculation layer is a pure TypeScript module with full unit test coverage. It handles the standard two-monthly and six-monthly filing periods, calculates output tax (from sales) and input tax credits (from expenses), and produces the net GST payable or refundable figure.

Edge cases — zero-rated exports, exempt supplies, and partial input tax credits — are handled explicitly with clear explanations shown to the user.

Filing Guidance

Rather than attempting direct IRD integration (which requires a tax agent intermediary), the app produces a step-by-step guided walkthrough for submitting the return through myIR, the IRD's own portal. This keeps the app legally straightforward while still removing 90% of the friction.