Primary sourcesGOV.UK "Tax codes: what your tax code means", "Tax overpayments and underpayments" (P800 / Simple Assessment), "Claim a tax refund" and "Income Tax: general enquiries" + HMRC "Report suspicious HMRC emails, texts and phone calls" + Low Incomes Tax Reform Group (LITRG) on tax refunds and tax-refund companies
Last verified9 June 2026
ConfidenceHigh — the standard 2026/27 code 1257L and the £12,570 Personal Allowance (frozen to at least 2028), the meaning of L / BR / D0 / D1 / 0T / NT / K and the emergency W1 / M1 / X codes, and the S (Scotland) / C (Wales) prefixes are confirmed on GOV.UK's tax-codes guide. The P800 / Simple Assessment process, online claim and ~5-working-day timing, and the 4-year claim limit are confirmed on GOV.UK and LITRG. The scam and rebate-company facts are confirmed by HMRC's phishing guidance and LITRG.
Key ruleCheck your tax code free in your HMRC Personal Tax Account / app; claim any P800 refund online and keep 100%. You can usually claim back overpaid tax for the last 4 tax years. HMRC never sends a refund link by text or email — those are scams — and you never need a paid rebate firm.
ScopeUK-wide (Scotland and Wales have their own Income Tax rates, shown by an S or C in the code). Tax rates, allowances and processes change each year — always check the current position on GOV.UK and, if unsure, take free advice from LITRG or Citizens Advice.