Methodology
Return to Work Payback 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
monthlyNetGain = monthlyNetPay − monthlyChildcare − monthlyCommute − monthlyOtherRecurringWhere
- monthlyNetPay
- Monthly net pay (currency units/month)Source: User assumption
- monthlyChildcare
- Monthly childcare (currency units/month)Source: User assumption
- monthlyCommute
- Monthly commute (currency units/month)Source: User assumption
- monthlyOtherRecurring
- Other recurring costs (currency units/month)Source: User assumption
- monthlyNetGain
- Monthly net gain from working (currency units/month)Source: Calculated output
paybackMonths = monthlyNetGain > 0 ? oneTimeReturnCosts ÷ monthlyNetGain : not availableWhere
- oneTimeReturnCosts
- One-time return costs (currency units)Source: User assumption
- paybackMonths
- One-time cost payback (months)Source: Calculated output
horizonNetGain = monthlyNetGain × horizonMonths − oneTimeReturnCostsWhere
- oneTimeReturnCosts
- One-time return costs (currency units)Source: User assumption
- horizonMonths
- Comparison horizon (months)Source: User assumption
- horizonNetGain
- Net gain over horizon (currency units)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
4,000 net pay less 1,500 childcare, 300 commute and 400 other costs, with 3,000 one-time cost.
Calculation and outputs
Example
4,000 net pay less 1,500 childcare, 300 commute and 400 other costs, with 3,000 one-time cost.
- Monthly net gain from working
- 1,800.00 currency units
- One-time cost payback
- 1.67
- Net gain over horizon
- 18,600.00 currency units
The engine returns 1,800 monthly gain, 1.67-month payback and 18,600 over 12 months.
Interpretation
Use monthly net gain and payback together; no positive monthly gain means no payback.
3. Validation and boundary checks
- The worked example is calculated through the same shared-work-logic engine as the planner.
- Non-finite and out-of-range assumptions return an input error.
- Result cards, trace, CSV, PDF and methodology bind to named engine result fields.
4. Assumptions and source classification
- Net pay and recurring costs are supplied by the user.
- Monthly values remain constant over the horizon.
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
- No tax, subsidy, eligibility or childcare-policy calculation is performed.
- Non-financial benefits and constraints are excluded.
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 Return to Work Payback planner and methodology.
Related reading
Use these practical guides to interpret the decision and its assumptions.
- How to use the Return to Work Payback calculator
Estimate monthly net gain, payback time and horizon value after user-entered recurring costs.
Read guide