Pro-Rata Salary Calculation Methods

This article explains the available methods for calculating partial-month salaries in the preliminary payroll. Pro-rata calculations are necessary when changes occur during a pay period — such as joining or leaving mid-month, salary changes, changes in compensation type (hourly to fixed or vice versa), or the start/end of a leave of absence. You can configure the calculation method at entity level under Settings > Payroll > Payroll Settings > General.

For all methods, public holidays are taken into account. Different countries may have different rules for pro-rata calculations — always verify the specific regulations for your company.

Actual Working Days

This method is based on the employee's actual working days as defined by their working time model. The monthly salary is divided by the total working days in the period.

Formula: Pro-rata salary = Monthly salary x (Employee's working days in period / Total working days in period)

Example — Exit mid-month: An employee earns 3,000 EUR/month and leaves on 15 March 2024. There are 11 working days from 1–15 March and 23 total working days in the period. Calculation: 3,000 x (11 / 23) = 1,434.78 EUR

Example — Salary change mid-month: An employee's salary increases from 3,000 EUR to 3,600 EUR on 20 April 2024 (5-day week, 22 total working days). 14 working days at the old rate, 8 at the new rate. Old portion: (3,000 / 22) x 14 = 1,909.09 EUR | New portion: (3,600 / 22) x 8 = 1,309.09 EUR | Total: 3,218.18 EUR

Monthly Fixed Salary — Working Days

This method uses a standardized number of working days per month (configurable to 21, 21.67, 21.75, or 22 days) and scales based on the employee's weekly working days. The pro-rata salary is capped at 100% of the monthly salary per salary portion — if the salary changes mid-month, each portion is capped separately.

Formula: Pro-rata salary = Salary x (Days worked in period / (Monthly avg. working days x (Weekly working days / FTE days)))

Example — Exit mid-month: An employee earns 3,200 EUR/month, leaves on 12 October 2024, average working days: 21, worked 9 days. Calculation: 3,200 x (9 / (21 x (5/5))) = 1,371.42 EUR

Example — Salary change mid-month: Salary increases from 2,800 EUR to 3,500 EUR on 17 May 2024, average working days: 21. 11 days at old rate, 10 at new rate. Old: 2,800 x (11/21) = 1,466.67 EUR | New: 3,500 x (10/21) = 1,666.67 EUR | Total: 3,133.34 EUR

Annual Fixed Salary — Working Days

This method calculates pro-rata compensation based on company-defined annual working days (default: 260 for a 5-day week). A daily rate is determined by dividing the annual salary by total annual working days.

Formula: Pro-rata salary = Monthly salary - (Daily rate x Monday–Friday days not worked in period) Daily rate = (Monthly salary x 12) / Annual working days

Example — Exit mid-month: An employee earns 36,000 EUR/year (3,000 EUR/month), leaves on 15 March 2024. Non-applicable working days: 8 (16–31 March). Daily rate: 36,000/260 = 138.46 EUR | Pro-rata: 3,000 - (138.46 x 8) = 1,892.31 EUR

Example — Salary change mid-month: Salary increases from 36,000 EUR to 42,000 EUR/year on 16 July 2024. Old daily rate: 138.46 EUR, 12 non-applicable days | New daily rate: 161.54 EUR, 11 non-applicable days. Old: 3,000 - (138.46 x 12) = 1,338.48 EUR | New: 3,500 - (161.54 x 11) = 1,723.06 EUR | Total: 3,061.54 EUR

Calendar Days — Annual

This method calculates a daily rate based on the total number of calendar days in the year (365, or 366 in a leap year).

Formula: Pro-rata salary = (Monthly salary x 12) x (Calendar days in period / Calendar days in year)

Example — Exit mid-month: An employee earns 3,000 EUR/month, leaves on 15 June 2024. Days in period: 14, calendar days 2024: 366 (leap year). Calculation: (3,000 x 12) x (14/366) = 1,377.05 EUR

Example — Salary change mid-month: Salary increases from 3,000 EUR to 3,500 EUR on 16 September 2024. Old portion: (3,000 x 12) x (259/366) | New portion: (3,500 x 12) x (107/366) | Total: 3,146.45 EUR

Monthly Fixed Salary — 30 Days

This method assumes a fixed 30 days for every month, regardless of actual calendar days or working time models.

Formula: Pro-rata salary = Salary x (Days in period / 30)

Example — Exit mid-month: An employee earns 3,000 EUR/month, leaves on 18 August 2024. Applicable calendar days: 18. Calculation: (3,000/30) x 18 = 1,800 EUR

Example — Salary change mid-month: Salary increases from 2,800 EUR to 3,400 EUR on 20 November 2024. 19 days at old rate, 11 at new rate. Old: (2,800/30) x 19 = 1,773.27 EUR | New: (3,400/30) x 11 = 1,246.63 EUR | Total: 3,019.90 EUR

Calendar Days — Monthly

This method divides the monthly salary by the actual number of calendar days in that specific month (e.g., 31 in January, 28/29 in February). No cap is applied, so compensation may exceed the new rate when changes occur mid-month.

Formula: Pro-rata salary = Salary x (Days in period / Days in month)

Example — Exit mid-month: An employee earns 3,100 EUR/month, leaves on 14 September 2024. Applicable days: 14, September has 30 days. Calculation: 3,100 x (14/30) = 1,446.67 EUR

Example — Salary change mid-month: Salary increases from 2,900 EUR to 3,500 EUR on 17 June 2024. 16 days at old rate, 14 at new rate, June has 30 days. Calculation: 2,900 x (16/30) + 3,500 x (14/30) = 3,180.00 EUR