Every Singapore employer faces the same recurring statutory deadlines: monthly CPF and SDL by the 14th, quarterly GST F5 one month after each quarter, and the annual IR8A/AIS filing by 1 March.
This page puts every recurring obligation in one place, with the dates, who it applies to, and links to the detailed guide for each one.
Monthly
CPF contributions
Due by the last day of the month; late payment grace to the 14th of the following month. Applies to all Singapore Citizens and Permanent Residents. Total rate is up to 37% (17% employer + 20% employee) for employees aged 55 and below on the new S$8,000 OW ceiling.
CPF contribution rates 2026 →Skills Development Levy (SDL)
0.25% of each employee’s wages (min S$2, max S$11.25). Collected alongside CPF, same deadline. Applies to all employees including foreign workers.
SDL guide →Itemised payslips
Must be issued to every employee within 3 days of salary payment. Required under the Employment Act for all employees covered by the Act.
Foreign Worker Levy (FWL)
Monthly levy for each Work Permit and S Pass holder. Amount varies by sector, worker qualification, and dependency ratio ceiling. Billed by MOM separately from CPF.
Quarterly — GST F5
GST F5 is due one month after each accounting period ends. For most businesses filing quarterly:
| Quarter | Period ends | F5 due |
|---|---|---|
| Q1 | 31 Mar | 30 Apr |
| Q2 | 30 Jun | 31 Jul |
| Q3 | 30 Sep | 31 Oct |
| Q4 | 31 Dec | 31 Jan |
Applies to all GST-registered businesses. NIL returns required even for quarters with no transactions.
GST F5 filing guide →Annual — the 1 March cluster
Three major annual obligations converge on 1 March 2026 for income earned in 2025:
IR8A / AIS
Annual return of each employee’s employment income. Mandatory electronic filing (AIS) for employers with 5+ employees. Deadline is strict — IRAS does not grant routine extensions.
IR8A / AIS guide →Appendix 8A
Benefits-in-kind: housing, car benefit, club memberships. Filed alongside IR8A for each employee it applies to.
Appendix 8B
Gains from employee share options (ESOP) or share awards (ESOW). Filed alongside IR8A.
IR21
Tax clearance for employees who cease employment or plan to leave Singapore. Due at least one month before departure or last day of employment.
Ongoing — InvoiceNow
GST-registered businesses must transmit invoice data via InvoiceNow from their mandatory date. Since 1 April 2026, all new voluntary GST registrants must be on an InvoiceNow-Ready Solution. Existing businesses are phased in by annual supplies through 2031.
InvoiceNow deadline guide →The penalties, at a glance
| Obligation | Penalty |
|---|---|
| CPF / SDL late payment | 1.5% per month interest (18% p.a.) on outstanding amount |
| IR8A late / inaccurate | Fines up to S$5,000, up to 2× tax undercharged, possible imprisonment |
| GST F5 late filing | Immediate $200, then $200/month outstanding, capped $10,000/return |
| GST late payment | Immediate 5% on unpaid tax, then 2%/month after 60 days, capped 50% |
The practical rhythm
Every month
Run payroll → calculate CPF + SDL → submit to CPF Board by the 14th → issue itemised payslips within 3 days of payment → pay FWL if applicable.
Every quarter (if GST-registered)
Reconcile output and input tax → file GST F5 via myTax Portal → pay net GST by the deadline → transmit InvoiceNow data if in scope.
Every year (by 1 March)
Reconcile full-year payroll against CPF → generate IR8A for every employee → prepare Appendix 8A/8B where needed → submit via AIS (or give employees their IR8A if below 5 staff).
Where Critical Mass Cloud fits
Critical Mass Cloud handles CPF, SDL, IR8A/AIS, GST returns and InvoiceNow in one Singapore-native platform. Each deadline maps to a workflow that runs from your live data rather than a year-end reconstruction.
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What are the key employer deadlines in Singapore?
CPF and SDL monthly by the 14th, GST F5 quarterly one month after each period, and IR8A/AIS annually by 1 March. InvoiceNow compliance dates vary by wave.
When is CPF due each month?
CPF contributions are due by the last day of the calendar month. If late, payment must be made by the 14th of the following month before 1.5% per month interest applies.
What is the IR8A deadline?
1 March 2026 for income earned in 2025. It is fixed — IRAS does not grant routine extensions.
When is GST F5 due?
One month after each accounting period ends — both the return and the payment. For a quarter ending 31 March, that is 30 April.
What happens if I miss a deadline?
Penalties vary by obligation: CPF/SDL incurs 1.5% monthly interest, IR8A can mean fines up to S$5,000 and prosecution, and late GST filing starts at $200 immediately plus $200 per month outstanding.