Payslip Checker for Swansea on Tax Code SD1

Swansea is a mid-sized urban economy of around 250k residents in South Wales. Median full-time gross pay for the area sits near £28,400 per year (ONS ASHE 2024), and most local employees see their PAYE deducted before they ever check the breakdown. This page focuses specifically on what tax code SD1 should look like on a Swansea payslip. Because SD1 is a stable PAYE code, the monthly figures should be broadly consistent across the tax year. Welsh residents normally see a C-prefixed code; SD1 does not carry that prefix, so check whether HMRC has the right address for you.

What does SD1 mean for Swansea workers?

SD1 applies a flat 42% to every pound under this employment. In Swansea, this is most often a second-job code — for example NHS bank shifts at a local trust on top of a substantive role. Swansea employers occasionally drop the C prefix during payroll-system migrations, especially after staff move from England.

Scottish equivalent of D1. All income under this employment is taxed at the Scottish higher rate (42% in 2026/27). Used on additional sources of income for higher-band Scottish taxpayers.

Effective tax + NI rate on this salary: 46.5%. Estimates based on ONS ASHE median earnings 2024 — your actual pay may differ.

Local context for Swansea

Welsh residents are charged the Welsh Rate of Income Tax. Although the rates are currently aligned with rest-of-UK rates for 2026/27, the C prefix is still required for HMRC to allocate revenue correctly. Swansea employees who recently moved from England should confirm HMRC has updated the address — otherwise the C prefix can drop off the next payslip. The Welsh-language HMRC helpline operates from Cardiff and Porthmadog.

Common payroll questions in Swansea

Should my Swansea payslip show tax code SD1?

SD1 should appear if your circumstances match what HMRC expects for this code (scottish higher-rate flat code at 42%.). On a typical Swansea salary of £28,400 you would expect roughly £994 of income tax per month under this code.

Why does my Swansea payslip differ from a colleague's on the same code?

Two Swansea colleagues on tax code SD1 can still see different deductions because pension contributions, salary sacrifice, student loan plan, taxable benefits and overtime all sit alongside the tax code. The code only governs the income-tax line. Match the code first, then check pension and NI category, then the variable lines.

Does the Welsh Rate of Income Tax change my Swansea take-home on SD1?

For 2026/27 the Welsh rates align with rest-of-UK rates, so the take-home is materially the same. The C prefix is still required so HMRC can allocate revenue to Wales — not because it changes your tax bill.

What should I do if SD1 looks wrong on my Swansea payslip?

Start with your most recent payslip and your latest HMRC P2 coding notice. If the code on your payslip does not match the code on the P2, the employer is the right first call. If they match but the figure looks wrong, contact HMRC on 0300 200 3300 — your tax code is set by HMRC, not by your Swansea employer. You can also upload your payslip to PayslipIQ for a free instant breakdown.