Incomplete Month Salary Calculator
Updated November 2026 · Free · No sign-up
Calculate incomplete month salary in Singapore — the exact MOM formula using working days, for mid-month joiners, leavers, and no-pay leave, with the worked examples payroll teams use.
Quick answer: MOM formula: (monthly gross ÷ total working days in the month) × days actually worked, where working days = the employee's required days (usually Mon-Fri or Mon-Sat). Joining 15 September on S$5,000 (22 working days, 12 worked) = S$2,727.
The MOM Formula (Employment Act)
Salary for incomplete month = (Monthly gross rate of pay ÷ Total number of working days in that month) × Days the employee actually worked
Key definitions that decide disputes:
- Working days in the month = the days the employee is REQUIRED to work that month (a Mon-Fri worker: 20-23 depending on the calendar; Mon-Sat: 24-27) — NOT a fixed 22 or calendar 30.
- Days worked includes paid public holidays and paid leave taken within the employment period.
- Gross rate includes fixed allowances; excludes OT, bonuses, reimbursements.
Worked Examples
Example 1 — mid-month joiner. S$5,000, September with 22 working days, joined the 15th (12 working days remained incl. a PH): 5,000 ÷ 22 × 12 = S$2,727.27.
Example 2 — the month-length effect. Same 12 days worked in a 20-working-day February: 5,000 ÷ 20 × 12 = S$3,000 — the divisor is the month's own count, so identical attendance pays differently across months. Correct, not an error.
Example 3 — no-pay leave. Full month minus 3 NPL days in a 21-day month: 5,000 ÷ 21 × 18 = S$4,285.71 — equivalently, deduct 3 × (5,000/21). Same formula both directions (the Indian LOP equivalent uses fixed divisors; Singapore's floats).
Example 4 — leaver mid-month. Last day the 10th (7 working days of 23): 5,000 ÷ 23 × 7 = S$1,521.74 + leave encashment per the pro-rated leave calculator.
What Rides on the Prorated Figure
| Item | Treatment |
|---|---|
| CPF | Computed on the prorated actual wage — see the CPF calculator |
| Fixed allowances | Prorate with the same formula (part of gross rate) |
| AWS/13th month | Separate proration by completed months |
| Notice offsets | Short-notice recoveries price at the same working-day rate |
The Three Classic Payroll Errors
- Calendar-day division (÷30/÷31) — undercounts the daily rate and underpays joiners who start before weekends; MOM's formula is working-days.
- Fixed-22 divisors — overpays in long months, underpays in short ones; the divisor must be THAT month's required days.
- Dropping paid PHs from "days worked" — a public holiday inside the employment period counts as worked.
Disputes route through TADM/MOM — with the formula statutory, the math usually settles them in one email.
Regional Note
Malaysia's Employment Act uses calendar-day proration (÷26 convention for daily-rate math) and India floats between calendar and fixed divisors by policy — cross-border payroll teams shouldn't copy one country's formula into another; each page in this cluster carries its own jurisdiction's rule.
Frequently Asked Questions
How is salary calculated for an incomplete month in Singapore?
(Monthly gross ÷ total working days in that month) × days actually worked — the statutory MOM formula; the divisor is that month's required working days, not 30 or a fixed 22.
Do public holidays count as days worked?
Yes — paid public holidays and paid leave within the employment period count in the numerator.
Why does the same number of days pay differently in different months?
The divisor floats with each month's working-day count (20-23 for Mon-Fri) — February days are worth more than August days. Statutorily correct.
What is included in gross rate of pay?
Basic plus fixed allowances; excludes overtime, bonuses, incentives, and reimbursements.
How is no-pay leave deducted?
Same formula in reverse: deduct (gross ÷ working days of the month) per NPL day.
Where do I dispute a wrong proration?
TADM mediation/MOM — the formula is statutory, so documented math typically resolves it quickly.
✓ Formula verified • Last updated: November 3, 2026