Employee and employer pension contributions plus tax relief.
Your details
Total annual contribution
£3,600
You £2,250 · Employer £1,350
Tax + NI relief
£450
Impact on take-home
| Take-home before pension | £35,920 |
| Take-home after pension | £34,120 |
| Change in take-home | -£1,800 |
Interactive scenarios
Tax and deductions, your way
Tax year
Region
Pay schedule
Salary £45,000
Net (monthly)
£2,806
Income tax (monthly)
£541
NI (monthly)
£216
Effective rate
20.2%
The full guide
Worked examples with real figures, the order payroll applies them in, and the traps that catch people out.
A pound into a pension costs a basic rate taxpayer eighty pence of take home and a higher rate taxpayer sixty. Inside the allowance taper it costs forty.
That is the whole case for modelling a contribution rather than guessing at one. The pot grows by more than your payslip falls, every single month.
A pound in the pot costs a basic rate taxpayer eighty pence of take home and a higher rate taxpayer sixty. Inside the allowance taper it can cost forty. The band you sit in sets the price.
Salary sacrifice removes the contribution from gross pay, so it avoids National Insurance as well as income tax. Relief at source takes it from net pay and HMRC adds the basic rate back, leaving higher rate taxpayers to claim the rest through self assessment.
Employer matching outweighs a small salary difference within a couple of years, and the gap keeps widening for the rest of a working life.
Where each pound goes
Where each pound of salary lands
Moving from five percent to six adds £450 a year to the pot. Take home drops by roughly £26 a month for a basic rate taxpayer, so £312 a year buys £450.
Under salary sacrifice the contribution leaves gross pay, so it dodges National Insurance too and the monthly cost falls again. Under relief at source a higher rate taxpayer has to claim the extra relief through self assessment, and plenty never do.
An employer match changes the maths entirely. Six percent from an employer on £48,000 beats four percent on £50,000 inside two years, and the gap widens for the rest of a career.
Worked payslip
Gross to net, line by line
Sample payslip
Month 06 · 2025/26Gross pay
£2,916.67
Pension (5%)
£145.83
Taxable pay
£2,770.84
Income tax
£373.83
National Insurance
£149.52
Net pay
£2,247.66
New pay stacks on top of old pay, so it is charged at the rate of the band it lands in rather than your average rate. A £3,000 rise that crosses the higher rate threshold can hand over roughly £1,240 of itself.
Run the current salary, note the net. Run the new one, note the net. The difference between those two figures is the only number worth celebrating.
Then route part of the rise into the pension. Take home barely moves, the pot jumps and the tax bill falls. On the wrong side of a threshold that trade is close to free money.
Sixty payslips turn small monthly differences into serious money. A £40 monthly gap is £2,400 across five years before anything grows.
Pension shows it hardest. Two extra percent on £45,000, matched by an employer and topped by relief, adds close to £2,000 a year to the pot. Compound that for thirty years at a modest rate and it clears six figures.
Multiply the monthly gap by sixty for the cash answer, then apply growth to the yearly pension gap for the long one.
Leave window
The same decision, five years apart
Rates, bands and thresholds follow published HMRC and gov.uk figures for the 2025/26 tax year, held in one table that every tool reads. April arrives, the table changes, and the results move together.
Earlier years stay available through the year selector, so a late self assessment runs on the numbers that applied at the time rather than today's.
Some cases still need an accountant. K codes carrying negative allowances, bespoke sacrifice arrangements, the annual allowance taper for very high earners, and anything involving two employments at once.
Pension Contribution Calculator answers one question. The salary calculator turns gross into net, the income tax calculator splits the bill by band, the National Insurance calculator shows the step at the upper limit, and the pension calculator prices a percentage change three ways at once.
Every tool reads the same rate table, so two pages never disagree. Run this one, note the figure, then open the next and watch which line moves.
Cash is the floor of a decision, not the decision. An hour a day handed back by a shorter commute is roughly two hundred and fifty hours a year, and nothing prices that against a manager worth working for.
Some benefits convert cleanly. Health cover has a taxable value, a learning budget has a receipt, extra leave has a daily rate. Share options that vest over four years and enhanced parental leave do not, so weigh those separately rather than treating them as salary.
Example gallery
Real inputs, real outputs
Graduate starter
First job, default workplace pension.
Gross / yr
£28,000
Pension
5%
Income tax
£3,086
NI
£1,234
Mid career
Standard tax code, modest pension uplift.
Gross / yr
£45,000
Pension
6%
Income tax
£6,486
NI
£2,594
Higher rate
Crossing the higher rate band.
Gross / yr
£72,000
Pension
8%
Income tax
£16,232
NI
£3,451
Scotland mid
Scottish bands applied.
Gross / yr
£45,000
Pension
5%
Income tax
£6,928
NI
£2,594
About this calculator
Model how a pension contribution, from both you and your employer, affects your annual contributions, the tax relief you receive, and your take-home pay.
Quick reference
Questions are added here as readers send them in.