Can a deed of variation be entered into after the second anniversary of the deceased's death to preserve a transferable nil rate band?

The transferable nil rate band

If a person leaves their entire estate to their spouse or civil partner, by reason of the transferable nil rate band (NRB), there is a potential tax free allowance of up to £650,000 on the death of the second to die. The transferable NRB would be reduced in value if the first person to die gifted their estate to beneficiaries other than the spouse or civil partner, such as children. See generally: Inheritance tax (IHT)—overview, and Practice Notes: IHT—nil rate band (NRB) and transferable NRB and Calculating the inheritance tax (IHT) charge on death.

On the death of the surviving spouse or civil partner, the executors can claim a transfer of the unused NRB from the first death. The claim and supporting documents are sent to HMRC when the inheritance tax (IHT) form 400 is submitted on the death of the surviving spouse