Updated for the 2026/27 tax year
The CD0 tax code
All your income from this job or pension is taxed at the higher rate in Wales
What it does to your pay
CD0 charges 40% on everything from this job or pension — the Welsh higher rate for Wales. There is no tax-free amount and there are no band steps: the whole payment is taxed at that one rate, from the first pound.
Codes like this are normally used on a second job or a second pension, where your allowance is already being used up by the first one. If it is on your ONLY income, that is the case worth querying — you may be paying tax on an allowance you are entitled to.
Source: Reg 7(3)(b) read with reg 7(2B) and ITA s.6B.
A worked example
On pay of £30,000 for the year, CD0 makes £30,000 taxable and produces £12,000 of income tax. The standard code on the same pay would produce £3,486, so this code costs £8,514 more over the year.
- £30,000 at 40% = £12,000
Income tax only — National Insurance, student loan repayments and pension contributions are separate and are not included here.
How CD0 is written on a payslip
CD0 is the code. Anything printed after it is a marker, and the markers this site recognises are W1, M1, X and NONCUM — HMRC’s payroll names for the non-cumulative basis, which the regulations set out at regs 26–31 and which the emergency-code page explains in full. Whether a marker changes anything for THIS code is a question for the regulation quoted above, not for the marker.
The space is optional and payslips print it both ways. CD0 W1 and CD0W1 are the same string as far as this site is concerned: the checker upper-cases what you type and strips the spaces out before it looks the code up, so either spelling reaches this page.
One character in CD0 is worth checking twice: the 0 is the DIGIT zero, not the letter O. Typed as CDO it is not a code this site can decode — the checker answers “malformed” rather than guessing — and it is a common enough mistype that it is worth looking at your payslip again before concluding the code itself is wrong.
Is it right for you?
Check whether this is your only income. A flat-rate code on a sole job means your Personal Allowance is not being applied anywhere, which is usually wrong and usually recoverable.
Whatever the answer, the code HMRC holds for you is the one that governs, and it is on your Personal Tax Account. If your tax code is wrong sets out how to get it changed.
Common questions
What does the CD0 tax code mean?
All your income from this job or pension is taxed at the higher rate in Wales. It charges 40% on the whole payment with no tax-free amount and no band steps.
How much tax does CD0 take on £30,000 a year?
On pay of £30,000 for the year, CD0 makes £30,000 taxable and produces £12,000 of income tax. The standard code on the same pay would produce £3,486, a difference of £8,514 over the year. Income tax only — National Insurance, student loan repayments and pension contributions are separate and are not included.
Is CD0W1 the same code as CD0?
Yes. W1, M1, X and NONCUM are the markers HMRC uses for the non-cumulative basis, and a marker after CD0 leaves the code itself unchanged. The space is optional: this site's checker reads CD0W1 and CD0 W1 identically, because it strips spaces before looking the code up.
Is it CD0 with a zero, or CDO with the letter O?
A zero. The 0 in CD0 is the digit, and this site's checker treats CDO as malformed rather than guessing which you meant — so if you typed it with the letter and got nothing back, that is why.
Independent tool not affiliated with HMRC. For your official code, log in to your Personal Tax Account. Check your tax code on GOV.UK.
Letters and law are not the same thing. The PAYE Regulations create these codes by describing what they DO — “the basic rate code”, “the nil tax code” — and, with one exception, never write down the letters HMRC prints on your payslip. The letters are HMRC’s naming for those functions. This site labels which is which on every page, and the sources page shows the search behind that statement.
The figures and rules on this site are taken from the Income Tax (Pay As You Earn) Regulations 2003, the Income Tax Act 2007 and HMRC’s published guidance, and are shown as they were found. They have not been signed off by a reviewer. Where the law and HMRC’s naming differ, the page says which is which rather than blending them. For anything that affects a decision, the cited document governs and this site does not.