The GST F5 form (Form 5) is your periodic GST return, and it's due one calendar month after your accounting period ends. For a quarter ending 31 March, that's 30 April. Every GST-registered business must file — even a quarter with no transactions needs a NIL return with zeros in every box. Miss it and IRAS charges an immediate $200, then another $200 for each month it stays outstanding, up to $10,000 per return.
GST is a 9% consumption tax. The F5 reconciles the GST you collected (output tax) against the GST you paid (input tax); the difference is what you pay IRAS or get refunded.
The essentials
| What | GST F5 — periodic GST return |
| Cycle | Quarterly by default (monthly or half-yearly on IRAS approval) |
| Deadline | One month after accounting period ends — return AND payment |
| How | e-File via IRAS myTax Portal (Corppass, "GST (Filing and Applications)" Approver role) |
| Currency | All figures in SGD |
| Late filing | Immediate $200, plus $200/month outstanding, capped at $10,000/return |
| Late payment | Immediate 5% on unpaid tax, then 2%/month after 60 days, capped at 50% |
GST filing periods and their due dates: Jan–Mar → 30 Apr · Apr–Jun → 31 Jul · Jul–Sep → 31 Oct · Oct–Dec → 31 Jan.
The eight boxes
Total standard-rated supplies (9% sales, excluding GST)
Zero-rated supplies (exports, international services)
Exempt supplies (financial services, residential property)
Total supplies (1+2+3)
Total taxable purchases (excluding GST)
Output tax due (9% on Box 1, plus adjustments)
Input tax claimed
Net GST: Box 6 − Box 7. Positive = pay IRAS; negative = refund.
The portal calculates Boxes 6 and 8 but check against your accounting software's GST summary before submitting.
How to file, step by step
- 1Reconcile first. Match invoices, permits, credit/debit notes against ledger. Confirm GST codes before starting.
- 2Log in to mytax.iras.gov.sg with Corppass. Need GST (Filing and Applications) Approver role.
- 3Open the return: GST → File GST Return (F5/F7/F8) → select period.
- 4Enter consolidated figures. Apply 9% to standard-rated, 0% to zero-rated, account for reverse charge.
- 5Check Box 6 and Box 8 against internal GST summary. Reconcile variances.
- 6Review declaration and submit. Keep acknowledgement.
- 7Pay by deadline. GIRO auto-deducts ~15th of month after due date.
Two things that trip people up
NIL quarter still files
Zeros in every box, or you're penalised.
Corrections use GST F7
You cannot edit a submitted F5. File a GST F7 (amendment). Final return = GST F8.
The InvoiceNow change
From 1 April 2026, new voluntary GST registrants must transmit invoice data via InvoiceNow. F5 deadlines unchanged but clean InvoiceNow-ready records matter more each year. See our InvoiceNow deadline guide.
Where Critical Mass Cloud fits
Tracks output/input tax as you invoice through the quarter. F5 boxes populated from clean data at filing time. Built InvoiceNow-ready.
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- GST InvoiceNow deadlines
- IR8A / AIS submission
- InvoiceNow-Ready Solutions
- Singapore SME compliance calendar 2026 — every payroll & tax deadline in one place
Questions
When is GST F5 due?
One month after accounting period ends — both return and payment.
What are the penalties for late GST filing?
Immediate $200, then $200/month, capped $10,000. Late payment: 5% immediate, 2%/month after 60 days, capped 50%.
Do I file if I had no sales?
Yes. NIL return with zeros required.
What’s the difference between F5, F7 and F8?
F5 = normal return. F7 = correction. F8 = final return on deregistration.
How do I correct a mistake after submitting?
Can’t edit submitted F5. File GST F7.
What is Box 8?
Net GST: Box 6 minus Box 7. Positive = pay IRAS; negative = refund.
Where do I get the GST F5 form?
There is no separate paper form to download. The GST F5 is filed electronically via the IRAS myTax Portal — log in with Corppass, navigate to GST → File GST Return, and complete it online.