Rates used
The calculator uses the 2026/27 full new State Pension rate of £241.30 per week and a simplified one-thirty-fifth annual accrual. The default full-year Class 3 cost is £956.80, based on £18.40 for 52 weeks.
Useful years
The model limits the number of years counted by the gaps entered, future years expected, the usual 35-year framework and the remaining headroom between the entered forecast and the full rate.
Tax and break-even
Annual uplift is reduced by the selected marginal tax rate. Break-even equals modelled purchase cost divided by estimated after-tax annual uplift. Lifetime value equals the uplift over the selected pension period less the purchase cost.
Known limitations
The calculation cannot reproduce DWP's individual transitional calculation, confirm that a particular gap is payable, identify NI credits, account for future uprating or predict tax rules. Always verify each year before paying.