IHTM25531 - AR/BR 100% relief allowance: transfer of unused allowance – basic principles
Unused 100% relief allowance from a late spouse or civil partner may be transferred to the deceased’s estate.
This transfer of the unused 100% relief allowance can apply where, on the death of the first spouse or civil partner, they did not use the full business property and/or agricultural property 100% relief allowance.
The guidance on what constitutes a valid marriage or civil partnership, set out at IHTM43003-IHTM43005, will apply to transfers of the unused 100% relief allowance.
The transfer of unused 100% relief allowance may be claimed on the death of the surviving spouse or civil partner where that death occurred on or after 6 April 2026.
For married couples, the first death can have occurred at any time before or after 6 April 2026. The transferable 100% relief allowance is therefore available where the first death occurred under Inheritance Tax, Capital Transfer Tax or Estate duty.
For civil partners the first death must have occurred on or after 5 December 2005, the date the Civil Partnership Act became law in the United Kingdom. While it was possible to enter into a civil partnership in other countries before this date, the Act states that where a relationship was recognised under overseas law before the UK Act came into force, the parties to the relationship are to be treated as having formed a civil partnership recognised in the UK on the date the Act came into force.