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Methodology

Salary Sacrifice or Pre-Tax Benefit Impact methodology

Compare one pre-tax benefit scenario using only a user-entered flat tax rate and benefit value.
Duc Nguyen X.By Duc Nguyen X.· Founder, Wage101Last reviewed: View update historyMethodology

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

Total value change
totalValueDelta = totalValueAfterSacrifice − baselineCash

Where

totalValueDelta
Total value change (currency units/period)Source: Calculated output
totalValueAfterSacrifice
Cash plus entered benefit value (currency units/period)Source: Calculated output
baselineCash
Baseline cash at entered tax rate (currency units/period)Source: Calculated output
Total after-sacrifice value
totalValueAfterSacrifice = cashAfterSacrifice + benefitValue

Where

benefitValue
Benefit value (currency units/period)Source: User assumption
totalValueAfterSacrifice
Cash plus entered benefit value (currency units/period)Source: Calculated output
cashAfterSacrifice
Cash after sacrifice and entered tax (currency units/period)Source: Calculated output
Cash after sacrifice
cashAfterSacrifice = taxablePayAfterSacrifice − taxAfterSacrifice

Where

cashAfterSacrifice
Cash after sacrifice and entered tax (currency units/period)Source: Calculated output
taxablePayAfterSacrifice
Taxable Pay After Sacrifice (currency units/year)Source: Calculated output
taxAfterSacrifice
Tax After Sacrifice (currency units/year)Source: Calculated output
Baseline cash
baselineCash = grossPay − baselineTax

Where

grossPay
Gross pay (currency units/period)Source: User assumption
baselineCash
Baseline cash at entered tax rate (currency units/period)Source: Calculated output
baselineTax
Baseline Tax (currency units/year)Source: Calculated output
Tax difference
taxDifference = baselineTax − taxAfterSacrifice

Where

taxDifference
Tax difference at entered rate (currency units/period)Source: Calculated output
taxAfterSacrifice
Tax After Sacrifice (currency units/year)Source: Calculated output
baselineTax
Baseline Tax (currency units/year)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

Compare 500 sacrifice from 5,000 gross pay at an entered 30% rate with 500 benefit value.

Calculation and outputs

Example

Compare 500 sacrifice from 5,000 gross pay at an entered 30% rate with 500 benefit value.

Total value change
150.00 currency units
Cash plus entered benefit value
3,650.00 currency units
Cash after sacrifice and entered tax
3,150.00 currency units
Baseline cash at entered tax rate
3,500.00 currency units
Tax difference at entered rate
150.00 currency units

Baseline cash, after-sacrifice cash and entered benefit value remain distinct.

Interpretation

Compare cash and entered benefit value without inferring tax eligibility.

3. Validation and boundary checks

  • Sacrifice amount cannot exceed gross pay.
  • Entered UI tax rate stays between 0 and 1.
  • Money inputs are finite and non-negative.

4. Assumptions and source classification

  • The user-entered flat rate applies before and after sacrifice.
  • The entered benefit value is additive to after-sacrifice cash.
  • All values use one pay period.

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 official salary-sacrifice, pre-tax benefit, tax or payroll eligibility rule is applied.
  • The benefit may have different tax or cash-flow treatment in reality.
  • This is not tax or benefit advice.

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

  1. : Initial public release of the Salary Sacrifice or Pre-Tax Benefit Impact planner and methodology.

Related reading

Use these practical guides to interpret the decision and its assumptions.

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