Three GST checks in one place: paste expense lines to catch blocked input tax (Regulations 26 & 27) and reverse-charge triggers, paste income lines to sort supplies into standard-rated, zero-rated, exempt and out-of-scope — with a three-question s21(3) walkthrough for international services — and run the F5 sanity checks before you file. Classification runs on our server against the rule set (your lines are held in memory for the request only — never stored); the F5 checks and walkthrough run entirely in your browser. A quick email verification unlocks classification.

Input tax — blocked & reverse charge

Straight from a GL export or expense listing — tabs, commas or spaces before the amount all work.

Output tax — supply classification

Supplies marked ZR? need the s21(3) walkthrough — three questions resolve whether the service zero-rates.

F5 return sanity checks

Assumptions & limits (beta)

  • Blocked input tax follows Regulations 26 and 27: S-plate motor cars and their running costs, club subscription fees, staff medical expenses and medical/accident insurance (WICA exceptions noted), family benefits, and betting transactions. Entertainment is not blocked for GST — unlike income tax.
  • Reverse charge flags are candidates, not conclusions — RC applies to imported services (and LVG) where you are not entitled to full input tax credit. Confirm your residual input tax position.
  • The s21(3) walkthrough is a simplified three-question test for international services (belonging, connection with Singapore land/goods, local direct beneficiary). Edge cases — s21(3) limbs with their own conditions, registered local beneficiaries from 2023 — resolve to “review”, not a conclusion.
  • De Minimis (Reg 28): exempt supplies within the lower of S$40,000 average per month and 5% of total supplies — input tax fully claimable; breaching it triggers apportionment (Regs 29–30, not computed here).
  • The output-tax expectation check allows a small tolerance for credit notes and rounding; investigate anything larger. Suggestions are keyword-based and editable — confirm every line before filing.
  • Privacy: classified lines are processed in server memory for the request only — never stored, never logged. F5 figures and walkthrough answers never leave the browser. See the site terms and data policy.

s21(3) walkthrough — international services

1. Does the customer belong outside Singapore (business establishment / usual residence overseas)?
2. Are the services directly in connection with goods or land situated in Singapore?
3. Does any person in Singapore directly benefit from the services (or is the customer in Singapore when they are performed)?
Beta — an early build, so expect bugs and rough edges. Double-check its output before you rely on it, and tell me what’s broken — I keep improving the tools people actually use.