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HMRC internal manual

Inheritance Tax Manual

Other issues: settling the amount of unused TNRB at the first death

Our published guidance sets out the recommended actions to be taken by the personal representatives of the first spouse or civil partner to die. Because of the potential for the circumstances of the surviving spouse or civil partner to alter between the two deaths, in which case any work undertaken on agreeing the amount of transferable nil rate band may potentially be wasted, any requests to agree the amount on the first death should be declined. 

Where the estate on the first death will not be taxable, but there are nevertheless chargeable elements, you should not seek to settle the chargeable estate on the first death. You should, however, note up any points that would be appropriate to take up had there been a liability so that when the file is reviewed on the second death, the issues can then be raised – if they are worthwhile at that time.