HMRC letter codes · Tax credits (TC)
TC689Allow someone to help with your tax credits
Last reviewed 14 October 2026 · How Tax Letters checks its facts
GOV.UK says tax credits ended on 5 April 2025 and no more payments will be made.
GOV.UK: Tax credits: general enquiries · checked 14 October 2026
In short
GOV.UK says form TC689 is for when you want an intermediary, such as Citizens Advice, to help you with your tax credits.
“Use form TC689 if you want an intermediary, such as Citizens Advice, to help you with your tax credits.”
GOV.UK: Tax credits: allow someone to help you with your award (TC689) · checked 14 October 2026
Information, not advice: this page reports what HMRC, GOV.UK and the bodies named publish about TC689. Each fact has its source and the day it was checked beside it.
What it asks
GOV.UK says form TC689 is sent to HMRC and has to be signed by the person, or persons on a joint claim, being represented.
“Send form TC689 to HMRC. This must be signed by the person (or persons if it’s a joint claim) you’re representing.”
GOV.UK: Dealing with tax credits for someone else · checked 14 October 2026
GOV.UK says an authorisation given on form TC689 can be cancelled by writing to HMRC.
“An authorisation can be cancelled by writing to HMRC.”
GOV.UK: Dealing with tax credits for someone else · checked 14 October 2026
Time limits and rules
GOV.UK says form TC689 is not for authorising a paid agent such as an accountant or other professional adviser, and points to form 64-8 for that.
“Do not use form TC689 to authorise a paid agent such as an accountant or other professional adviser to help you with your tax credits. You should use form 64-8 instead.”
GOV.UK: Tax credits: allow someone to help you with your award (TC689) · checked 14 October 2026
GOV.UK says an authorisation made on form TC689 lasts 12 months unless a different end date is put on the form.
“The authorisation lasts 12 months unless a different end date is put on the form.”
GOV.UK: Dealing with tax credits for someone else · checked 14 October 2026
GOV.UK's page on dealing with tax credits for someone else, which names form TC689, says no new claims can be made.
“Tax credits have ended. No new claims can be made.”
GOV.UK: Dealing with tax credits for someone else · checked 14 October 2026
Free help and HMRC contacts
GOV.UK names Citizens Advice as an example of an intermediary who can help with your tax credits through form TC689.
“such as Citizens Advice, to help you with your tax credits”
GOV.UK: Tax credits: allow someone to help you with your award (TC689) · checked 14 October 2026
Free help first
These routes are described by GOV.UK, TaxAid and Citizens Advice themselves.
- HMRC's extra supportHMRC offers extra support if your health condition or personal circumstances make it difficult to contact HMRC, for example a mental health condition, financial hardship or being treated in hospital.
- Someone to deal with HMRC for youYou can authorise a friend, relative or voluntary organisation to talk to HMRC for you and help you fill in forms.
- TaxAidTaxAid helps people with tax problems who cannot pay for advice. Tax Help for Older People merged with TaxAid in July 2025.
- Citizens AdviceCitizens Advice gives confidential advice online, over the phone and in person, for free.
- GOV.UK: Tax credits: allow someone to help you with your award (TC689) (checked 14 Oct 2026)
- GOV.UK: Dealing with tax credits for someone else (checked 14 Oct 2026)
- GOV.UK: Tax credits: general enquiries (checked 14 Oct 2026)
- GOV.UK: Get help from HMRC if you need extra support (checked 7 Oct 2026)
- GOV.UK: Appoint someone to deal with HMRC on your behalf (checked 7 Oct 2026)
- TaxAid: About us (checked 8 Oct 2026)
- Citizens Advice: About us (checked 7 Oct 2026)