NHS Back Pay Calculator

Work out arrears for a late pay point increment, a regrade or promotion, acting up or a pay award, with an honest after-tax figure and a check against what you were actually paid.

Looking for this year's award instead? Try the NHS Pay Rise Calculator 2026/27. Updated October 2026.

Short answer

NHS back pay is (pay you should have had minus pay you were paid) x the time it covers. Pick what was backdated, your old and new pay points and the two dates, and the calculator gives the days backdated, the gross arrears and an estimate of what the lump sum is worth after tax, National Insurance and pension. For a Band 5 nurse moving from point 1 to point 2 from 1 June, with arrears worked out to 11 September, that is £704 gross, about £36 after deductions. Enter what you were actually paid to see any shortfall.

What was backdated?

You moved up a pay point on your increment date but payroll paid the old rate for a while.

Where you work

Northern Ireland uses the England scale here because its 2026/27 award is not yet confirmed.

Pay you were actually paid
Pay you should have been paid

Your inputs are saved on this device only.

Back pay owed (gross)

£704

102 days (about 14.57 weeks, 3.35 months) at £210 a month more.

Pay you were paid£32,073
Pay you should have had£34,592
Difference per year£2,519.00
Difference per week£48.31

If paid as a lump sum on top of normal pay this tax year

Income tax-£23.19
National Insurance-£56.30
NHS Pension contribution-£587.85
Estimated net value£36.46

Enter the gross back pay on your payslip and we will show any shortfall.

When are you owed NHS back pay?

  • A late pay point increment. Your incremental date passed but payroll kept paying the old point. See pay progression and increments.
  • A regrade, promotion or job evaluation outcome that takes effect from an earlier date than your payslip changed. See how to challenge your pay band.
  • Acting up into a higher band without being paid the difference.
  • A pay award that reached your payslip after its effective date. See NHS pay rise 2026/27.
  • Wrong hours, enhancements or holiday pay. Use the Payslip Checker to spot which line looks off.

Whatever the cause, the fixed point is the date the higher pay should have started. The gap between that date and the date your payslip catches up is the arrears period.

Worked examples, 2026/27 pay points

Hypothetical dates, real 2026/27 England pay points, full time, in the NHS Pension Scheme:

ScenarioPay paid to pay dueDaysGross arrearsEstimated net value
Late increment: Band 5 point 1 to point 2, from 1 June 2026, worked out to 11 September 2026 £32,073 to £34,592 102 £703.80 £36.46
Regrade: Band 5 point 2 to Band 6 point 1, from 1 March 2026, worked out to 1 September 2026 £34,592 to £39,959 184 £2,702.96 £1,734.21
Part-time (22.5 hours): same late increment as the first row £19,244 to £20,755 102 £422.28 £282.09

The deductions are not a flat percentage. We work out take-home with and without the lump sum on top of normal pay, so the arrears are charged at the marginal rate they really attract. For the regrade example, tax, National Insurance and pension take £968.75 of the £2,702.96.

How a back pay lump sum is taxed

Arrears are taxed as pay in the month you receive them, whichever period they cover. Your normal salary already uses your Personal Allowance and some of your basic-rate band, so the lump sum sits on top. If it is large relative to your salary, part of it can be taxed at a higher marginal rate. That is how progressive tax works, not a payroll error.

ℹA pay-period spike is usually a timing effect

Income tax is cumulative across the tax year for the same employer, so a big arrears payslip can have more tax taken than turns out to be right for the year, and it usually corrects on later payslips or through HMRC at year end. National Insurance is worked out per pay period and does not reconcile in the same way. Check the following payslip, and speak to payroll or HMRC if a large payment lands near the tax year boundary or alongside a tax code change.

How far back can you claim, and what to do first

Time limits for underpayment claims are short. A tribunal claim for unlawful deductions from wages generally has to be started within six months (less a day) of the last underpayment for wages due on or after 1 October 2026, and three months (less a day) for earlier ones, which Acas early conciliation can extend, and for a series of underpayments recovery is normally limited to the previous two years. Contract claims have different limits. These are general points, not legal advice: speak to your union representative or Acas early. See NHS staff representation, unions and royal colleges.

  1. Work out the figure with the calculator and note your dates and pay points.
  2. Ask payroll, in writing, to confirm your pay point history and how the arrears were or will be calculated.
  3. Check the payslip lines with the Payslip Checker.
  4. If it is not resolved, raise it with HR and involve your union representative.

What this calculator does not do

  • • It uses basic pay only: enhancements, overtime and London weighting are not modelled.
  • • It uses the 2026/27 pay scales for both points. For arrears across a pay award or earlier years, use My own figures with your own salaries.
  • • It does not know which payslip the arrears will land on or your trust's exact pay period boundaries.
  • • It does not model salary sacrifice or arrears that span more than one tax year.

Sources and accuracy

  • ✓ Pay points: NHS Employers, pay scales 2026/27.
  • ✓ Tax, National Insurance and pension tiers: the same engine as the NHS Pay Calculator.
  • ✓ Your inputs are saved only on your own device and never sent anywhere.
  • ✓ Last updated October 2026. Read our editorial policy. This is information, not legal advice. FrontlinePay is independent and not affiliated with the NHS.

Frequently asked questions

How do I calculate NHS back pay? +
Work out the difference between the pay you should have received and what you were paid, then multiply by the time it covers. Annual difference divided by 365.25 gives a daily figure, times the number of days between the date the higher pay should have started and the date arrears are calculated to. The calculator does this from your pay points and dates, then estimates what the lump sum is worth after tax, National Insurance and pension.
When am I owed back pay in the NHS? +
Common situations: your pay point increment was processed late, a regrade or promotion took effect from an earlier date than your payslip changed, you acted up into a higher band without being paid the difference, a pay award reached your payslip after its effective date, or your hours or enhancements were wrongly paid. The calculator has a starting point for each. If you are unsure whether you are owed anything, ask payroll to explain your pay point history.
Is NHS back pay taxed? +
Yes. Arrears are taxed as normal pay in the month you receive them, whichever period they relate to. A lump sum sits on top of your normal salary, so part of it can be taxed at a higher marginal rate in that pay period. Income tax is cumulative across the tax year, so it often evens out on later payslips or at year end, but National Insurance is charged per pay period and does not self-correct in the same way.
How long does my trust have to pay back pay? +
There is no single national deadline for processing arrears, but pay is contractual, so underpayment should be corrected promptly. Ask payroll in writing for the date it will be paid and how it was calculated. If it drags on, raise a grievance with HR and speak to your union representative.
How far back can I claim? +
Time limits are strict. A tribunal claim for unlawful deductions from wages generally has to be started within six months (less a day) of the last underpayment for wages due on or after 1 October 2026, and three months (less a day) for earlier ones, extended by Acas early conciliation, and for a series of underpayments the amount you can recover is normally limited to the previous two years. Contract claims have different limits. Get advice from your union or Acas quickly rather than waiting.
My increment was missed. Is it backdated automatically? +
It should be corrected from your incremental date once payroll spots it, but you may need to ask. Check your payslip for the pay point, compare it with your contract or last increment letter, and use the calculator to see what you should receive. Our pay progression guide explains when you move up a pay point.
I have been acting up. Can I claim the difference? +
Where you have been asked to carry out a higher-banded role, you should normally be paid for it, and many trusts have an acting-up policy setting the threshold and rate. Ask HR for the policy, keep a record of dates and duties, and put your request in writing. The calculator shows the sum for a period you enter, and our regrading guides explain the formal routes.
How is back pay worked out for part-time staff? +
Scale both pay points to your contracted hours. For example, someone on 22.5 hours (60% of full time) moving from Band 5 point 1 to point 2 from 1 June 2026, with arrears calculated up to 11 September 2026, is owed about £422.28 gross. The calculator scales for you when you enter your hours.
Why is the tax on my back pay higher than I expected? +
Because a lump sum is added to that month's pay, it is tested against that month's allowance and bands, so more of it can be taxed at 40% or at a higher National Insurance rate than the same money spread over several months. Over the whole year income tax usually reconciles, and the calculator's 'net value' reflects the position for the tax year as a whole.
I was paid some back pay. How do I know if it is right? +
Enter the gross back pay from your payslip in the 'already been paid' box and the calculator shows any shortfall against its figure. A gap does not prove an error, since your trust may count different dates or pay points, but it tells you what to ask. The Payslip Checker helps with the payslip lines themselves.
Is the NHS pay award back pay different? +
The mechanics are the same: the award has an effective date (1 April for the 2026/27 Agenda for Change award) and any gap before it reaches your payslip is arrears. For 2026/27, NHS Employers confirmed most Agenda for Change staff were paid the award in April 2026 salaries, so the award scenario is mainly for payroll that ran late. See our pay rise calculator and guide.
Is NHS back pay pensionable? +
Arrears of basic pay are pay for the earlier period, so NHS Pension contributions are normally deducted from them, and the pension is built on that pay for the year it relates to. The calculator includes the pension contribution when you tick the NHS Pension box. Ask NHS Pensions or payroll how arrears for a previous scheme year are treated if you are close to a contribution tier boundary.
Will back pay change my tax code? +
A lump sum does not change your tax code by itself. It is simply taxed through PAYE in the month you receive it. If a payslip with back pay looks over-taxed, ask payroll whether the tax will be adjusted on later payslips, and check your tax code on your HMRC online account if anything else has changed.
Does a back pay lump sum affect Universal Credit? +
It can. Universal Credit looks at your earnings in each monthly assessment period, so a large back pay payment can reduce that month's award even though it relates to earlier months. If you claim Universal Credit, tell your work coach about the payment and ask how it will be treated.

More tools and guides

NHS Pay Rise Calculator 2026/27

Before and after for your band and point.

Payslip Checker

Check each payslip line.

NHS Pay Calculator

Take-home pay by band and point.

NHS pay progression and increments

When you move up a pay point.

How to challenge your NHS pay band

Job evaluation and appeals.

Overpayment of wages: your rights

If you are paid too much instead.

NHS Pay Protection Calculator

If your band went down.

Rota and Take-Home Calculator

A whole month, correctly taxed.

NHS Back Pay Claim: Free Check and Pack

Free readiness check and time-limit guide, then claim letter with calculation table, payroll records request, escalation letter, grievance wording, follow-ups and rep briefing.