HMRC letter codes
The code on your letter, explained.
Last reviewed 14 October 2026 · How Tax Letters checks its facts
Many HMRC letters and forms carry a code. Find yours below. Each code page reports what HMRC, GOV.UK or a recognised body publishes about it, with the source and the day it was checked beside each fact.
Every letter code, by series
Self Assessment (SA)
- SA1Register for Self Assessment
- SA401Register a partner
- SA250Welcome letter
- SA316Notice to file a tax return
- SA100Main tax return
- SA101Additional information pages
- SA102Employment pages
- SA103SSelf-employment pages, short
- SA103FSelf-employment pages, full
- SA104SPartnership pages, short
- SA104FPartnership pages, full
- SA105UK property pages
- SA106Foreign pages
- SA107Trusts pages
- SA108Capital gains summary pages
- SA109Residence and non-resident pages
- SA110Tax calculation summary pages
- SA200Short tax return
- SA800Partnership tax return
- SA302Tax calculation
- SA300Self Assessment statement
- SA303Claim to reduce payments on account
- SA359Strongly worded payment reminder
- SA326DPenalty notice for a late tax return
- SA372Daily penalty reminder
- SA370Notice of penalty assessment
- SA371Partnership notice of penalty assessment
- SA251Exit letter
- SA252Higher rate or complex tax code letter
Corporation Tax (CT)
- CT600Company Tax Return
- CT603Notice to deliver a Company Tax Return
- CT41GInformation for a newly incorporated company
- CT41G (Clubs)Details of a new club, society or similar body
- CT208Payment and return reminders
- CT211Penalty determination for a late Company Tax Return
- CT220Corporation Tax assessment
- CT620Notices, determinations and assessments after a return
- CT61Return of Income Tax on company payments
- CT630Group Payment Arrangements Closure Notice
- CT631Group Payment Arrangements Apportionment Notice
- CT600AClose company loans and arrangements to confer benefits on participators
- CT600CGroup and consortium relief
- CT600ECharities and Community Amateur Sports Clubs
- CT600LResearch and development
VAT
- VAT1Application to register for VAT by post
- VAT1ARegistering for VAT when distance selling into Northern Ireland
- VAT1BRegistering for VAT on acquisitions into Northern Ireland
- VAT2Partnership details for VAT
- VAT7Cancelling a VAT registration by post
- VAT68Transferring a VAT registration
- VAT484Changes to VAT registration details
- VAT652Print-and-post VAT error correction form (withdrawn)
- VAT655VAT Notice of Assessment
- VAT656VAT Notice of Amendment of Assessment
- VAT426Reclaiming input tax for an insolvent trader after deregistration
- VAT427Reclaiming input tax after VAT registration is cancelled
- VAT126VAT refund for an organisation not registered for VAT
- VAT65AVAT refund for a business registered outside the UK
National Insurance (CA)
- CA5603Apply to pay voluntary National Insurance contributions
- CA5403Request your National Insurance number by post
- CA2490Home Responsibilities Protection eligibility letter
- CA4361National Insurance refund letter
- CA72ADefer National Insurance when you have more than one job
- CA8480Refund of self-employed National Insurance
- CF83Pay voluntary National Insurance for periods abroad
- CA5601Pay self-employed National Insurance by Direct Debit
- CA5610Refund of self-employed National Insurance, profits-based
- CA307Refund of UK National Insurance paid while working abroad
- CA82Appeal a National Insurance credits decision
- CA3822Certificate of coverage for working temporarily abroad
- CA3837Certificate for working temporarily abroad while self-employed
- CA8421Certificate for working in several countries
Child Benefit (CH)
- CH2Child Benefit claim form
- CH24AAsk for a Child Benefit or Guardian's Allowance decision to be looked at again
- CH105Allow someone to help you with your Child Benefit
- CH995Authorise a tax adviser for the High Income Child Benefit Charge
- CH459Tell HMRC your child has left education or training
- CH299Apply for extended Child Benefit
- CH193Tell HMRC a child is looked after by a local authority
Tax credits (TC)
- TC600Tax credits claim form
- TC602Tax credits award notice
- TC603DAnnual Declaration form
- TC603RAnnual Review form and finalisation pack
- TC603URAward Review form for ending a tax credits award
- TC607Statement of Account
- TC610Notice to pay
- TC825Income working sheet
- TC846Dispute recovery of an overpayment
- TC956Disability helpsheet
- TC689Allow someone to help with your tax credits
- TC1131Your tax credits overpayments
One-to-many letters
- NISPAR1MMNational Insurance paid over State Pension age
- LCL2REG2MMClass two National Insurance and State Pension
- CompC1LPLRMMLetter about income from property lettings
- CompC1LPLR(A)MMCovering letter to agents about property lettings letters
- HEIPO2MMLetter saying a business may need to register for VAT
- CI357MMLetter about income from online marketplace sales
- CompC1OMSCMMLetter about income from online marketplace sales
- MM1aHICBCSALetter asking whether the High Income Child Benefit Charge is due
- HICBCDS1gMMLetter about the High Income Child Benefit Charge and paying through a tax code
- CompC1ABMMLetter about income from breeding or selling animals
- CompC2ABMMLetter about income from breeding or selling animals, with a disclosure route
- CIHT1MMLetter to agents about cryptoassets in Inheritance Tax returns
- CTL24MMLetter about differences in the loss position of Company Tax Returns
- WS1NSAMMLetter saying a Self Assessment return may be due, first of three
- WS2NSAMMLetter saying a Self Assessment account is closed and a return may be due, second of three
- WS3NSAMMLetter saying a registered taxpayer has not submitted a return, third of three
- PROR2aMMLetter about a provisional Business Asset Roll-over Relief claim, earlier of two
- PROR2bMMLetter about a provisional Business Asset Roll-over Relief claim, later of two
- CompC1MPMMLetter asking a consultant to check Self Assessment returns for consultancy fees
- CAMM3MMLetter about tax on cryptoasset transactions
- GHO1MMLetter about a Gift Hold-over Relief claim
- LTATY2MMLetter saying a Business Asset Disposal Relief claim took the reader over the lifetime limit
- LTAAO2(A)MMLetter saying the Business Asset Disposal Relief lifetime limit was already reached
- AIA3MMLetter about Annual Investment Allowance claims and groups of companies
- PF1MMLetter inviting a call before a Self Assessment return is sent
- IRInd1MMLetter asking a reader to check an incorporation relief claim
- CompC11aESSMMLetter about sales that were not declared, with a final opportunity to make a disclosure
- CompC11bESSMMLetter about sales that were not declared, with a final opportunity to make a disclosure
- CompC1MRRMMLetter asking a company to check it paid the right amount of Corporation Tax
- CompC2MRRMMLetter asking a company to check it claimed the right Marginal Relief
- CompC1CRYPTOMMLetter about Capital Gains Tax on cryptoassets
- CompC2CRYPTOMMLetter about Capital Gains Tax on cryptoassets
- CompC1IDMMLetter about distribution or dividend income that may need declaring
- CPCE2024008MMLetter to charities about aggregated Gift Aid donations
- OTM000778Letter asking a reader to update a Self Assessment return with final figures
- OTM000648Letter about income from online marketplace sales
- OTM000559Letter about income from delivery work
- OTM000574Letter to agents about provisional figures in clients’ returns
- OTM000568Letter to agents about possible errors in clients’ Self Assessment returns
- R&D2MMLetter asking a company to check its Research and Development tax relief claim
- CompC1aESSMMLetter about undeclared sales and a chance to make a disclosure, version a
- CompC1bESSMMLetter about undeclared sales and a chance to make a disclosure, version b
136 codes in 8 series. Information, not advice: these pages report what HMRC and GOV.UK say; your own letter comes first.
Other codes
- Compliance check factsheets (CC/FS)The factsheets HMRC's compliance letters name, such as CC/FS1a and CC/FS7a.
- Tax code decoderThe tax code on a payslip or P2 notice, letter by letter.
- Every HMRC letterBrowse by kind of letter, with an A to Z of codes.
Free help first
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- GOV.UK: Get help from HMRC if you need extra support (checked 7 Oct 2026)
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