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Answers · GST · a quarter ending 30 Sep 2026 is due 31 Oct 2026

GST F5 box by box, with a worked quarter

The GST F5 is the return every GST-registered business files after each accounting period, quarterly by default, and it is due one month after the period ends: a quarter ending 30 Sep 2026 is due by 31 Oct 2026, and the payment with it. Boxes 1 to 8 are the trading boxes: your supplies (1 to 4), your taxable purchases (5), the GST you charged (6), the GST you can claim back (7) and the difference (8).

You file it even in a quarter where nothing happened.

Computed from the rulebook Edition YA-2027 · sources verified through 24 Jul 2026

The boxes, in order

The return has 21 boxes. The first eight carry the trade and 13 is your revenue; 9 to 12 and 14 to 21 apply only to schemes or situations most companies are not in, and stay at zero for everyone else. The right-hand column is the worked quarter below.

BoxWhat goes in itWorked, S$
1Total value of standard-rated suppliesSales at the standard rate, before GST. Include reverse-charge and customer-accounting supplies if you have them.70,000.00
2Total value of zero-rated suppliesExports and international services, taxed at 0%.20,000.00
3Total value of exempt suppliesExempt supplies: bank interest, sale or lease of residential property, most financial services.150.00
4Total of boxes 1+2+3Boxes 1, 2 and 3 added together. IRAS reads box 4 as your total supplies.90,150.00
5Total value of taxable purchasesPurchases and expenses on which GST was charged, before GST, plus zero-rated purchases and imports. Not the blocked items.34,000.00
6Output tax dueThe GST you charged on box 1.6,300.00
7Input tax and refunds claimedThe GST you paid on box 5 and are entitled to claim back.3,060.00
8Net GST to be paid/claimedBox 6 less box 7. Positive, you pay; negative, IRAS refunds.3,240.00
9Goods imported under MES/3PL/other approved schemesImports under the Major Exporter Scheme, the Approved Third Party Logistics scheme or another approved scheme, where no GST was paid at the border.not computed
10Tourist refunds claimedRefunds made to tourists under the Tourist Refund Scheme.not computed
11Bad debt relief / reverse-charge refund claimsBad debt relief claimed, and reverse-charge refund claims.not computed
12Pre-registration input tax claimedGST on purchases made before you registered, claimable once, in your first return.not computed
13RevenueRevenue: the total from your accounts for the period, principal activity only.90,000.00
14Imported services subject to reverse chargeServices and low-value goods bought from overseas suppliers on which you must account for the GST yourself (reverse charge).0.00
15Electronic marketplace remote servicesRemote services supplied through an electronic marketplace you operate.not computed
16Redeliverer low-value goodsLow-value goods you deliver as a redeliverer.not computed
17Direct low-value goods suppliesLow-value goods you supply directly to Singapore consumers.not computed
18IGDS: deferred import GSTImport GST deferred under the Import GST Deferment Scheme.not computed
19IGDS: import GST payableImport GST payable under the same scheme.not computed
20IGDS: total deferredTotal deferred under the scheme.not computed
21IGDS: adjustmentsAdjustments under the scheme.not computed

Simpler Tax computes boxes 1 to 8, 13 and 14 from the posted books and shows the arithmetic under each. The boxes marked not computed print a word rather than a figure in its pack, and a period with a reverse-charge purchase in it is refused outright rather than filled in, because the matching input claim rides a recovery ratio the engine does not model. A business in one of those lanes should not rely on the app alone for its F5.

A worked quarter: 1 Apr 2026 to 30 Jun 2026

The documents

Eight documents, one return

A GST-registered trading company with a December year end. Its quarter holds three local sales, one export, one bank-interest credit, two supplier invoices and one petrol receipt. GST is at 9%.

DateDocumentNet, S$GST, S$
6 Apr 2026Tax invoice to a local customerSale, code SR50,000.004,500.00
14 May 2026Tax invoice to a local customerSale, code SR12,000.001,080.00
21 May 2026Export invoice, goods shipped overseasSale, code ZR: zero-rated20,000.000.00
3 Jun 2026Tax invoice to a local customerSale, code SR8,000.00720.00
28 Jun 2026Bank interest receivedSale, code ES33: exempt, Regulation 33150.000.00
12 Apr 2026Supplier invoice, stockPurchase, code TX30,000.002,700.00
2 May 2026Office rent, tax invoicePurchase, code TX4,000.00360.00
19 May 2026Petrol for the director's carPurchase, code BL: blocked, Regulation 271,000.0090.00
The fold

What lands in which box

BoxArithmeticS$
1The three standard-rated sales: 50,000.00 + 12,000.00 + 8,000.0070,000.00
2The export20,000.00
3The bank interest, an exempt supply150.00
470,000.00 + 20,000.00 + 150.0090,150.00
5The two supplier invoices: 30,000.00 + 4,000.00. The petrol is blocked and stays out34,000.00
6GST charged on the sales: 4,500.00 + 1,080.00 + 720.006,300.00
7GST paid on the two supplier invoices: 2,700.00 + 360.00. The 90.00 on the petrol is not claimable3,060.00
86,300.00 − 3,060.00, to pay by 31 Jul 20263,240.00
13Revenue for the period: the sales, 70,000.00 + 20,000.00. The interest is in box 3 and left out90,000.00

Every other box is zero: no scheme imports, no tourist refunds, no bad debts, no pre-registration claims, no reverse charge, no marketplace or low-value goods, no deferred import GST.

When it is due, and which quarters are yours

The return and the payment are due one month after the accounting period ends. Quarters are assigned by IRAS from the month your financial year ends in, so the financial year always closes a GST quarter:

Financial year ends inYour quarters end in
January, April, July, OctoberJanuary, April, July, October
February, May, August, NovemberFebruary, May, August, November
March, June, September, DecemberMarch, June, September, December

On GIRO, the deduction is taken on the 15th of the month after the due date. Monthly filing is available on application. S$200 for each completed month late, capped at S$10,000; and 5% on unpaid tax and 2% a month after that.

What never goes in box 5 or box 7

Some purchases carry GST you cannot claim, whatever the business use. They are left out of both box 5 and box 7, not entered and then reversed: a motor car and its running costs (a lorry, van or bus is not a motor car for this rule); club subscriptions; benefits for staff members' families; betting, gaming and lotteries; staff medical expenses and medical insurance, except where a work-related health risk requires them.

The petrol receipt in the worked quarter is the first of those: the 90.00 of GST on it is a cost, and the 1,000.00 does not go in box 5 either.

Correcting a return you already filed

Small errors can be swept into your next return. Bigger ones need an F7, which is a full re-file of the quarter, not a list of differences. The concession holds only if both are true: the net GST error across the affected periods is S$3,000 or less, and the error in every other box is within 5% of that period's box 4 (box 5 where there were no supplies). Errors can be corrected back 5 years.

Do it in Simpler Tax

The F5 pack, each box showing its arithmetic

Post the quarter's documents and the Tax screen issues the GST F5 pack for your own quarter: boxes 1 to 8 and 13 computed from the posted books, the sum behind each box one click away, a copy button beside every figure. A quarter the engine cannot vouch for is held with the reason on its cover rather than filled in. You type the boxes into myTax Portal and sign; Simpler Tax files nothing.

Download for Windows Simpler-Tax_1.0.0_x64-setup.exe · 55 MB · not signed yet · free · SHA-256 on the home page

Questions people ask

When is my GST return due?

One month after the end of the accounting period, and the payment is due the same day. A quarter ending 30 Sep 2026 is due by 31 Oct 2026. On GIRO the deduction comes on the 15th of the month after that.

Do I file a GST return when there was nothing to report?

Yes. A nil return is still a return, with zeros in every box, and it is due on the same date. Missing it draws the same late-filing penalty.

What goes in box 4?

Boxes 1, 2 and 3 added together: standard-rated, zero-rated and exempt supplies. It is the figure IRAS treats as your total supplies, which is why the 5% test for correcting an error is measured against it.

What if box 7 is bigger than box 6?

Box 8 comes out negative and IRAS refunds the difference. That is normal for an exporter, whose sales sit in box 2 with no output tax while its purchases still carry input tax.

What goes in box 13, revenue?

The revenue in your accounts for the period, from the company's principal activity, before GST. Exempt income declared in box 3 is left out; so is anything collected on someone else's behalf. Box 13 is a statistic: a wrong box 13 alone does not need a correction, only the right figure next time.

What is the GST rate?

9% on standard-rated supplies since 1 Jan 2024. The worked quarter charges 9% on every standard-rated sale and purchase.

I made a mistake in a return I already filed. Do I file an F7?

Not always. If the net GST error across the affected periods is S$3,000 or less, and every other box is within 5% of that period's box 4, you correct it in your next F5. Otherwise you file a GST F7 for that period, which is a full re-file of the return, not a list of differences. Errors can be corrected back 5 years.

Sources

Statutory figures on this page are read from the Simpler Tax rulebook at build time, edition YA-2027, every source last checked 24 Jul 2026. The rulebook entries named below are the ones this page was computed from; the IRAS pages are what they were verified against.