NHS Back Pay Calculator

Each year the NHS Staff Council agrees a pay award for Agenda for Change staff, effective from 1 April. Because negotiations typically conclude after April, the uplift is applied retrospectively — meaning staff receive a lump-sum payment covering the months between 1 April and the date the new rate appears on their payslip.

The formula is straightforward: (new annual salary − old annual salary) ÷ 12 × months backdated = gross arrears. The lump sum is then subject to the usual PAYE deductions before it reaches your bank account.

Recent back-pay timelines:

• 2024/25 — 5.5% award, back pay paid October 2024 (6 months backdated)
• 2025/26 — 3.6% award, back pay paid August 2025 (4 months backdated)
• 2026/27 — 3.3% award, back pay expected August 2026 (4 months backdated)

The exact payment date varies by Trust, but most NHS employers process back pay within the same payroll cycle once the nationally agreed pay circular is issued by NHS Employers.

Back pay is treated as normal earnings through PAYE. It is added to your regular salary in the month it is paid, which means four main deductions will apply:

• Income tax — The arrears are added to that month's gross pay. If the combined figure pushes you above £50,270 you will pay 40% on the portion above that threshold for that pay period. HMRC's cumulative tax system usually corrects any temporary overpayment through subsequent monthly adjustments.
• National Insurance — Employee NI is charged at 8% on earnings between £12,570 and £50,270 (2% above £50,270). Your back pay is included in that month's NI calculation.
• Pension contributions — NHS back pay is pensionable. The arrears may push your total pensionable pay into a higher contribution tier for that month, temporarily increasing your pension deduction percentage.
• Student loan — If you have an active student loan, 9% is deducted on earnings above the threshold for your plan type (Plan 1: £24,990; Plan 2: £27,295; Plan 5: £25,000 for 2026/27). The lump sum is included in that month's calculation.

If you believe you have been over-taxed in the month your back pay is received, check subsequent payslips — HMRC's cumulative PAYE system should refund the difference automatically within one or two pay periods.

If you work part-time, your back pay is calculated pro rata based on your contracted hours relative to the standard full-time equivalent (FTE) of 37.5 hours per week.

Formula:

FTE = contracted hours ÷ 37.5
Your gross back pay = full-time gross arrears × FTE

Worked example:

• Band 5 entry, 22.5 hours/week → FTE = 22.5 ÷ 37.5 = 0.6
• Full-time gross back pay (4 months at 3.3%) ≈ £340
• Your gross back pay = £340 × 0.6 = ~£204

Deductions (tax, NI, pension) are then applied to this reduced figure in the usual way. Part-time staff on multiple NHS contracts may receive separate back-pay payments from each employer.

When your back pay is processed, check your payslip via ESR (Electronic Staff Record) or your Trust's self-service portal. The payslip should itemise:

• Gross arrears — shown as a separate line (often labelled "Back Pay" or "Arrears")
• Tax deduction — the income tax charged on the combined pay for that month
• NI deduction — National Insurance on the combined earnings
• Pension contribution — may reflect a temporarily higher tier
• Student loan deduction (if applicable)
• Net amount — the final figure credited to your bank account

What to do if something looks wrong:

1. Compare the gross arrears figure against your own calculation using the formula above.
2. Check whether the correct spinal point and any HCAS supplement have been applied.
3. If there is a discrepancy, contact your Trust's payroll department — they can provide a detailed breakdown.
4. For tax queries, wait one to two pay periods for HMRC's cumulative adjustment before raising a case.

The annual Agenda for Change pay award — and therefore back pay — applies to AfC Bands 2–9 employed directly by an NHS organisation. The following groups are not covered:

• Agency staff — paid by the agency, not the NHS employer
• Locum workers — typically engaged on separate contractual terms
• Independent contractors — not on NHS payroll
• Volunteers — not employed under AfC terms
• Bank staff — eligibility varies by Trust; some Trusts backdate bank shift rates, others do not
• Medical & Dental staff — covered by a separate pay framework (DDRB recommendations)
• GP practice staff — employed by individual practices, not NHS Trusts; pay arrangements are subject to separate negotiations

If you are unsure whether your role qualifies, check your employment contract or contact your HR department.