Does the C prefix change my take-home?

No - not for 2026/27. The Welsh Rates of Income Tax mirror rUK exactly: 20%/40%/45%. The C prefix is administrative tracking, not a different tax burden.

Could Welsh rates diverge from rUK in future?

Yes. The Welsh government has powers under the Wales Act 2014 (commenced 6 April 2019) to set each rate at any whole or half number of pence in the £. So far it has set all three at 10p in £ (matching rUK). Any future divergence would be announced in the Welsh Budget (December) and take effect from 6 April.

Why does HMRC bother with a C prefix if the rates are the same?

For revenue allocation. HMRC needs to identify Welsh-taxpayer income to attribute the correct share of Income Tax revenue to the Welsh Consolidated Fund. The mechanism is the same as Scotland's S prefix but produces the same monetary outcome in 2026/27 because rates align.

Tax Code · 2026/27

C Tax Code Prefix: Welsh Taxpayer 2026/27

The C prefix (e.g. C1257L, CBR, CD0) identifies you as a Welsh taxpayer for Income Tax. Welsh rates for 2026/27 currently mirror rUK (20%/40%/45%) but the Welsh government has devolved rate-setting power.

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What the C prefix tax code means

C prefix on a tax code (C-1257L is the most common) tells PAYE that you are a Welsh taxpayer. Like Scotland, Welsh residence status is determined by where you live for the majority of the tax year, not your employer.

For 2026/27 the Welsh Rates of Income Tax (WRIT) are identical to rUK: 20% basic, 40% higher, 45% additional. The Welsh government has powers to vary these by whole/half pence in the £ at any rate but has not diverged them since devolution in 2019.

Personal Allowance is identical (£12,570) and NI is UK-wide. The C prefix is administrative - it confirms WRIT applies, not Scottish or Northern Ireland rates.

When you'll see C prefix

You moved to Wales and HMRC updated your residence record - usually 1-3 months after Government Gateway address change.
Your employer's payroll feed picked up the Welsh indicator from HMRC's real-time PAYE service.
You spent the previous tax year majority-resident in Wales and HMRC confirmed Welsh-taxpayer status for the current year.

What to do if you have a C prefix code

If correct: nothing - PAYE will apply the same rates as rUK in 2026/27. The C is informational.
If you moved out of Wales: update Personal Tax Account address. HMRC removes the C prefix at next payroll feed.
Verify against a Welsh-rates calculator - take-home should match rUK for 2026/27 since rates align.
Any incorrect application is corrected via subsequent PAYE adjustments or P800 reconciliation.

Worked example

On £45,000 gross in Wales (C1257L) vs England (1257L) for 2026/27: Income Tax identical at £6,486, NI identical, take-home identical. The C prefix is operational - it lets the Welsh government track Welsh-taxpayer revenue and gives them the ability to diverge from rUK rates in future Budget cycles.

Want to see the numbers for your own salary? Use the salary calculator and pick 2026/27 to see how C prefix interacts with your full take-home.

Frequently asked questions about C prefix

Does the C prefix change my take-home?: No - not for 2026/27. The Welsh Rates of Income Tax mirror rUK exactly: 20%/40%/45%. The C prefix is administrative tracking, not a different tax burden.
Could Welsh rates diverge from rUK in future?: Yes. The Welsh government has powers under the Wales Act 2014 (commenced 6 April 2019) to set each rate at any whole or half number of pence in the £. So far it has set all three at 10p in £ (matching rUK). Any future divergence would be announced in the Welsh Budget (December) and take effect from 6 April.
Why does HMRC bother with a C prefix if the rates are the same?: For revenue allocation. HMRC needs to identify Welsh-taxpayer income to attribute the correct share of Income Tax revenue to the Welsh Consolidated Fund. The mechanism is the same as Scotland's S prefix but produces the same monetary outcome in 2026/27 because rates align.

All UK tax codes →

Sources & further reading

All figures and definitions on this page reflect the 2026/27 UK tax year and are cross-checked against HMRC guidance.

HMRC — What your tax code means (official meanings for L, BR, D0, D1, K, 0T, NT, M, N, S, C, T)
HMRC — Income Tax rates and Personal Allowance (2026/27 bands and thresholds)
HMRC — Emergency tax codes (W1, M1 and X suffixes)
HMRC — Rates and thresholds for employers 2026 to 2027
HMRC — Your Personal Tax Account (check your current code and how it was calculated)
Our methodology & calculation sources →