What D0 means
The D codes are flat-rate codes. They give no tax-free pay and tax every pound from the job at one rate. D0 uses the higher rate. HMRC issues it for a second job or pension when your main income already fills your Personal Allowance and the basic-rate band, so any extra income is taxed at 40%.
| Code | Where | Rate on all pay from this job |
|---|---|---|
| BR | England and Northern Ireland | 20% (basic rate) |
| D0 | England and Northern Ireland | 40% (higher rate) |
| D1 | England and Northern Ireland | 45% (additional rate) |
| CD0 | Wales | 40% (Welsh higher rate) |
| SD0 | Scotland | 21% (intermediate rate) |
| SD1 | Scotland | 42% (higher rate) |
| SD2 | Scotland | 45% (advanced rate) |
| SD3 | Scotland | 48% (top rate) |
How PAYE applies D0 on a payslip
Pay for the period is rounded down to the whole pound and multiplied by 40%. There's no tax-free amount to subtract and no band to work through, so the tax is the same in month 1 as in month 9 for the same pay. The payslip shows D0 as the tax code and a single income tax figure.
National Insurance doesn't follow the tax code. Each job works it out on its own pay, so a second job paid below the £1,048 monthly Primary Threshold has no employee National Insurance even on D0.
Worked example, 2026/27
| Pay this month | D0 income tax | SD0 income tax | Employee NI (either) |
|---|---|---|---|
| £500.00 | £200.00 | £105.00 | £0.00 |
| £1,000.00 | £400.00 | £210.00 | £0.00 |
| £2,500.00 | £1,000.00 | £525.00 | £116.16 |
On £2,500 the National Insurance is 8% of the £1,452 above the £1,048 monthly threshold. The figures come from PayDocs' 2026/27 rule set, which follows HMRC's PAYE specification.
SD0 in Scotland
Scotland has six income tax rates, so its D codes line up differently. GOV.UK says SD0 taxes all income from the job at Scotland's intermediate rate, which is 21% in 2026/27. SD1 is the higher rate (42%), SD2 the advanced rate (45%) and SD3 the top rate (48%). So a Scottish taxpayer whose main income already reaches the intermediate band is taxed at 21% on a second job, which is what SD0 does.
What the employer does
- Use the code HMRC sends. HMRC emails you when an employee's code changes; update the payroll record before the next payday.
- Don't change D0 yourself, even if it looks harsh. Only HMRC can issue a different code.
- Show the code on the payslip so the employee can check it.
- If the employee thinks it's wrong, point them to their HMRC online account or the HMRC app.
Questions
Why am I on D0?
Because HMRC expects your income from your main job or pension to use up your tax-free allowance and the basic-rate band, so pay from this job falls in the 40% band.
Is D0 an emergency tax code?
No. It's a normal code for a second job or pension. It's only on an emergency basis if it also ends in W1, M1 or X.
What if my total income isn't that high?
Then D0 may be wrong and you could overpay. Check your income details in your HMRC online account; HMRC can move the code to BR or split your allowance, and refunds overpaid tax.
Sources
- GOV.UK — Tax codes: what your tax code means
- GOV.UK — Understanding your employees' tax codes: what the letters mean
- HMRC — Rates and thresholds for employers 2026 to 2027
- GOV.UK — Income Tax in Scotland
- HMRC — Specification for PAYE Tax Table Routines, version 24.0
Official sources checked 4 October 2026. This guide explains how pay documents work; it is not tax or legal advice.
