Is the Auto-Inclusion Scheme (AIS) Mandatory? (Singapore Employers)

Yes — if your business employed five or more people at any point in the previous year, joining the Auto-Inclusion Scheme (AIS) is compulsory, and that count includes full-timers, part-timers, company directors and board members. Once you are on AIS you stay on it, even if your headcount later drops below five. Under five employees, it is voluntary.

Last reviewed 4 June 2026 · Source: IRAS.

Who must join AIS

The threshold is five employees. If you employed five or more people at any time in the preceding calendar year, the Inland Revenue Authority of Singapore (IRAS) requires you to submit every employee's income electronically through AIS — there is no opt-out. The count is deliberately wide: full-time staff, part-timers, your salaried company directors, and board members all count toward the five (IRAS).

There is a second route into the scheme. Any employer already registered for AIS in an earlier year stays in it permanently, even if the team later shrinks below five. AIS is a one-way door — you join once and you remain.

Your situation	AIS this year?
5 or more employees at any point last year	Compulsory
Already registered for AIS in a prior year	Compulsory — permanent
Fewer than 5 employees, never registered	Voluntary
Was on AIS, headcount later dropped to 3	Compulsory — stays in

What counts as "five employees"

Bosses undercount because they picture only full-time hires. IRAS counts everyone on your payroll under a contract of service: the two full-timers, the weekend part-timer, you as a salaried director, and a fellow board member drawing fees through payroll. Counted concretely — 2 full-timers + 1 part-timer + 1 working director + 1 board member on payroll is already 5. That is the AIS line, and it is easy to cross without noticing.

The test is whether you crossed five at any time during the year — not your headcount on 31 December. Hire a fifth person in March who leaves in August and you are an AIS employer for that whole year.

The deadline, and what missing it costs

AIS submissions are due by 1 March each year, reporting the income your employees earned in the previous calendar year. Year of Assessment 2026, for instance, covers calendar-year 2025 income and was due 1 March 2026 (IRAS).

The penalty has teeth. An AIS employer that fails to submit by 1 March can be fined up to $5,000 under Section 94(1) of the Income Tax Act 1947 (IRAS). For a micro-business, a $5,000 fine for one missed electronic filing buys several years of payroll software outright.

Miss the date and the fine is per offence, not a token charge.

What AIS actually does for you

AIS sends each employee's salary, bonus, CPF and deductions straight to IRAS, which pre-fills those figures into the employee's own income tax return. Your staff never key in their employment income — it is already there when they log in to file (IRAS).

That is the real benefit, and it cuts both ways. Employees rarely dispute a figure they never had to type, so year-end queries drop. Staff can also confirm their employer is enrolled through the IRAS Search AIS Organisation tool, so the scheme quietly signals that your payroll is run properly. Without AIS you instead hand every employee a paper Form IR8A by 1 March and they copy the numbers across themselves — more transcription error, more "which box is this" landing back on you. What the form contains, and what each appendix covers, is in our guide to IR8A annual income reporting.

Should you join voluntarily under five staff?

For most small employers, yes. Even at three or four people, voluntary AIS turns year-end from a stack of forms into a single upload, and it removes the risk of an employee mistyping income and being queried by IRAS. The cost is near zero if your payroll software already files through AIS — and almost all do.

Voluntary registration opens between 1 April and 31 December each year for the following Year of Assessment (IRAS); register once and IRAS keeps you enrolled, with no annual re-application. The one case for waiting is a hand-run payroll with only a couple of staff and no software. Even then, the moment you hire your fifth person AIS becomes compulsory, so setting it up early is the cheaper path. If you are standing up payroll for the first time, get your first CPF submission running before tax season — AIS reports the same employee data.

How AIS and IR8A fit together

IR8A is the form; AIS is the channel. Employers not on AIS still prepare a physical Form IR8A for each employee by 1 March. AIS employers prepare the same underlying figures but transmit them electronically through approved payroll software or the IRAS portal, skipping the paper (IRAS).

One more change to flag: Form IR8S, once used to report excess CPF contributions, is abolished from Year of Assessment 2026 — those amounts now sit inside IR8A itself (IRAS).

Check your headcount across the whole year, not just today. If you touched five employees at any point, AIS is not a choice — and 1 March arrives sooner than payroll year-end ever feels like it should.