Methodology
Prorated Salary Calculator methodology
Educational only: Work and pay decision support, not tax, legal, financial or career advice.
Privacy: Calculations run locally; Wage101 does not receive your work or pay inputs.
Update policy: Reviewed when formulas or official dependencies change.
Scope: Market-neutral work and pay planning using your own assumptions.
1. Formulas and units
proratedSalary = annualSalary × eligibleUnits ÷ totalUnitsWhere
- annualSalary
- Annual salary (currency units/year)Source: Work record
- eligibleUnits
- Eligible units (selected units)Source: Work record
- totalUnits
- Total units (selected units)Source: Work record
- proratedSalary
- Prorated salary (currency units)Source: Calculated output
excludedSalary = annualSalary − proratedSalaryWhere
- annualSalary
- Annual salary (currency units/year)Source: Work record
- excludedSalary
- Excluded salary portion (currency units)Source: Calculated output
fraction = eligibleUnits ÷ totalUnitsWhere
- eligibleUnits
- Eligible units (selected units)Source: Work record
- totalUnits
- Total units (selected units)Source: Work record
- fraction
- Eligible fraction (share of annual salary)Source: Calculated output
Money inputs and outputs use the currency selected in the scenario without changing the canonical methodology. Pay, time, benefits and work-related costs use the units stated beside each input.
2. Worked example
Input assumptions
An annual gross salary of 84,000 with 9 eligible months out of a 12-month year.
Calculation and outputs
Example
An annual gross salary of 84,000 with 9 eligible months out of a 12-month year.
- Prorated salary
- 63,000.00 currency units
- Excluded salary portion
- 21,000.00 currency units
- Eligible fraction
- 75%
The result shows both the included and excluded portions of the annual salary.
Interpretation
Use the prorated amount as a simple eligible-period share of annual gross salary.
3. Validation and boundary checks
- A full eligible period returns the full annual salary.
- Zero eligible units returns zero prorated salary.
- Eligible units above total units return an input error.
4. Assumptions and source classification
- Eligible and total units use the same consistent basis.
- Months basis uses exactly 12 total units; calendar days use 365 or 366.
- The annual salary is gross before tax.
This calculator has no current policy-data dependency. Its work and pay assumptions are user supplied. Registered family-level regression suites exercise the shared work-logic engine and worked-result reconciliation.
5. Limitations
- This does not model payroll cut-offs, paid leave or local employment rules.
- Working-day conventions differ by employer and must be entered consistently.
- Rounding on an actual payslip may differ.
This is educational decision support, not personalised tax, legal, financial or career advice. Check the treatment of your circumstances under the rules that apply to you and seek qualified advice where appropriate.
6. Update and evidence policy
Registered family-level suites test formula invariants and example reconciliation; the release ledger records that coverage without claiming a separate oracle for every line of public copy. There is no official threshold or benchmark to refresh for this calculator. Work and pay inputs remain user-supplied because they vary by person, job and contract.
Change history
- : Initial public release of the Prorated Salary planner and methodology.
Related reading
Use these practical guides to interpret the decision and its assumptions.
- How to use the Prorated Salary calculator
Estimate the included and excluded portions of an annual salary using months, calendar days, working days or custom units.
Read guide