A new hire starts on 19 October. Another employee's last day is 13 November. A third takes three days of no-pay leave in December. Each of these employees has an incomplete month, and each needs a salary that is neither a full month's pay nor a rough estimate.
The Ministry of Manpower (MOM) sets out one formula for these situations: monthly gross salary ÷ working days in the month × days actually worked. The formula itself is simple. Most errors come from the two day counts, especially how public holidays and paid leave are treated.
This guide explains when a month counts as incomplete, how to apply the MOM formula, worked examples for joiners, leavers and no-pay leave, and what to check for CPF and final salary payments. Figures are current as of 27 October 2026.
Key Takeaways
An incomplete month is any month in which a monthly-rated employee does not work the full month. MOM's guidance on monthly and daily salary lists the situations that commonly cause it.
A new hire who starts on 19 October has not worked the first part of the month, so October is an incomplete month for that employee.
An employee whose last day of employment is 13 November has an incomplete November, whether they resigned, their contract ended or the employer terminated the employment.
Approved no-pay leave reduces the days actually worked. A monthly-rated employee who takes even one day of no-pay leave has an incomplete month for that period.
MOM also lists reservist training (in-camp training) as a cause of an incomplete month. Employers can generally claim make-up pay from the government for National Service reservist training, so check how your payroll records this.
The formula is designed for monthly-rated, full-time employees. Part-time employees are usually paid by the hour or day under their own contract terms, so the incomplete month formula is not normally used for them. If you are unsure which terms apply, start with the employee's Key Employment Terms. Our guide to hiring in Singapore covers the documents every employer should have in place.
Divide the monthly gross salary by the total working days in that month, then multiply by the number of days the employee actually worked.
(Monthly gross rate of pay) / (Total number of working days in that month) x Total number of days the employee actually worked in that month
Each of the three inputs needs to be defined carefully. The next two sections explain the day counts, and a later section covers what goes into the monthly gross rate of pay.
Total working days are the days in that month on which the employee is normally required to work. According to MOM:
The number of working days therefore changes from month to month and depends on the employee's work pattern. MOM publishes a table of monthly working days for common schedules on the same monthly and daily salary page.
Days actually worked are the working days in the month on which the employee was employed and not on no-pay leave. According to MOM, they include:
No-pay leave days and days before the start date or after the last day of employment are not counted.
The most common mistake we see is removing public holidays from the calculation, either by leaving them out of the month's working days or by not counting them as days worked. Some payroll guides online also exclude public holidays. Under MOM's approach, they are included in both numbers, which affects the result in any month with a public holiday.
The examples below assume a Monday to Friday work week and use the 2026 public holiday calendar. Amounts are rounded to the nearest cent.
Mei Ling joins on Monday, 19 October 2026, with a monthly gross salary of S$4,400.
Arjun's last day of employment is Friday, 13 November 2026. His monthly gross salary is S$4,620.
If the public holiday were wrongly left out of both counts, the calculation would become S$4,620 ÷ 20 × 9 = S$2,079, underpaying Arjun by S$121.
Farah earns S$5,060 a month and takes three days of approved no-pay leave in December 2026.
The same formula applies, but the number of working days changes. A 5.5-day week includes a half working day, usually on Saturday, and a 6-day week counts Saturdays as full working days. Use MOM's published table of monthly working days for these schedules, or set them up correctly in your payroll software, rather than reusing a Monday to Friday count.
Use the incomplete month formula to pay salary for a partial month, and the daily rate of pay for specific payments and deductions. MOM defines the daily gross rate of pay for a monthly-rated employee as:
12 x (Monthly basic rate of pay) / 52 x (average number of days an employee is required to work in a week)
For an employee earning S$4,400 on a 5-day week, this is (12 × S$4,400) ÷ (52 × 5) = S$203.08 per day.
Mixing the two methods is a common source of small but repeated payroll differences. Agree on one method per situation and record it in your payroll policy.
Monthly gross rate of pay includes the basic salary and allowances payable under the contract, but excludes variable and reimbursed amounts. According to MOM, it generally excludes:
If a fixed allowance forms part of the contractual monthly pay, include it before prorating. For a full breakdown of what employers pay on top of salary, see our article on employment benefits in Singapore.
CPF contributions are generally calculated on the wages actually payable for the month, so a prorated salary leads to prorated CPF. For Singapore Citizens and Permanent Residents, a few points need attention:
When bonuses or leave encashment are paid to a leaver, these are usually Additional Wages and subject to the annual Additional Wage ceiling. Our guide to payroll processing in Singapore covers the monthly CPF workflow in more detail, and our payroll accounting guide explains how to reconcile CPF payments with your records.
The deadline depends on how the employment ends. MOM's rules on paying salary set the following timelines for employees covered by the Employment Act:
For ongoing employees, salary must be paid at least once a month and within 7 days after the end of the salary period. Overtime pay is due within 14 days after the end of the salary period.
The final payment usually combines several items: the prorated salary for the last month, pay for any unused annual leave, salary in lieu of notice where applicable, and any deductions allowed under the contract. Prepare an itemised payslip that shows each component clearly.
If a non-Singapore Citizen employee is leaving your company, you may need to file Form IR21 with IRAS before releasing the final payment. Based on IRAS guidance on tax clearance for employees:
This interacts with the MOM final salary deadlines above, so plan the IR21 filing as soon as the employee's notice is received.
MOM's formula uses working days, not calendar days. Dividing by 30 or 31 calendar days gives a different result and does not follow MOM's guidance for monthly-rated employees.
Yes. A public holiday that falls on a normal working day is included in the month's working days. If it falls within the employee's period of employment, it also counts as a day actually worked.
Not quite. Approved no-pay leave is usually handled through the incomplete month formula. A deduction for unauthorised absence is generally calculated using the gross rate of pay per day. Record the two separately.
Generally not. Part-time employees are usually paid on an hourly or daily basis under their own contract terms. The incomplete month formula is designed for monthly-rated, full-time employees.
CPF is generally calculated on the wages payable for that month. For a new joiner, this is the prorated salary. Apply the contribution rates for the employee's age and residency status.
Only in specific cases. For foreign and Permanent Resident employees who need tax clearance, employers must withhold monies due until IRAS issues its clearance directive. Otherwise, the final salary must be paid within MOM's deadlines.
Incomplete months come up every time someone joins, leaves or takes unpaid leave, and small differences repeat quickly if the method is not consistent. ATHR's payroll team supports Singapore businesses with:
Every client works with a dedicated Key Account Manager who knows your team and your payroll calendar.
If you are hiring your first employees or want a second look at how your payroll handles incomplete months, explore ATHR's Payroll Management services or speak with our team.
This guide is for general information only and reflects MOM, CPF and IRAS guidance available as of 27 October 2026. It does not constitute legal, payroll or tax advice. Employment terms, contribution rates and deadlines may change, and the correct treatment depends on each employee's contract and circumstances. Please refer to the latest official publications or consult a qualified professional before acting on any information in this article. ATHR accepts no liability for any loss arising from reliance on this content.
The ATHR Content Team is a group of professional writers from Singapore and the Philippines, committed to delivering informative, practical, and engaging content for business owners across Southeast Asia.
