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Five tips for dealing with HMRC: trusts, estates and IHT

Author: ICAEW Insights

Published: 13 Mar 2025

Following a meeting with HMRC’s trust and inheritance tax (IHT) teams, ICAEW’s Tax Faculty has pulled together five tips which may help taxpayers and agents to complete tasks more quickly and HMRC to make best use of its resources.
  • Call HMRC at quieter times. For IHT, the best time to call HMRC is between 13:00 and 14:30. The helpline’s busiest periods are from 11:30 to 12:30 and from 15:00 to 17:00. The trust helpline is busiest between 14:00 and 15:30 and the best time to call is 13:00 to 14:00.
  • Consider having the unique HMRC code, that is needed by personal representatives when applying for probate (or confirmation in Scotland), to be sent by email. You can only do this by completing page 15 of the IHT400 form, otherwise the code will be sent by post. Personal representatives should ensure that the email address is spelt correctly and is legible.
  • Use form P1000, rather than form 64-8, for personal representatives to provide their details to HMRC. Further information is provided in a previous article.
  • Wait at least 12 weeks from submission before chasing a reply where the estate is a ‘simple estate’, ie, where the income tax and capital gains tax liabilities for the period of administration are dealt with as an ‘informal arrangement’, rather than via a SA900 trust return. Previously, personal representatives were asked to wait at least eight weeks from submission before chasing for a reply.
  • Consider using HMRC’s new IHT grossing up calculator. Grossing up is needed where some gifts in the Will are left ‘free of tax’ and the IHT is borne by the rest of the estate.  
The Tax Faculty

ICAEW's Tax Faculty is recognised internationally as a leading authority and source of expertise on taxation. The faculty is the voice of tax for ICAEW, responsible for all submissions to the tax authorities. Join the Faculty for expert guidance and support enabling you to provide the best advice on tax to your clients or business.

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