Backdated purchase of NHS Additional Pension

[hiriskpaul]

My sister in law tried to purchase additional pension last financial year, but due to total incompetence and/or the coronavirus, this was not processed by the end of the financial year. However, the NHS pension bureaucrats have said they will accept payment as though it was made last financial year. The issue though is how HMRC will view this. Ideally she would like the payment to be considered to have happened last year so that she can claim a refund against last year's tax. That will give her the option of either buying more this year and/or contributing to her SIPP.

Does anyone know whether HMRC will allow her to claim against last year's tax?