IHT refund

I am intending to do a deed of variation on my late mother's will so as to give some of the legacy I have received from her to charity. I understand that this will mean a refund of the Inheritance Tax that has already been paid on this charitable donation. I have two questions. 1. Does HMRC pay interest on the IHT refund? 2. If the answer to Q1 is 'Yes' - is that interst taxable? Thank you.

Hi,
Please contact the Inheritance Tax team for advice.
https://www.gov.uk/government/organisations/hm-revenue-customs/contact/probate-and-inheritance-tax-enquiries
How Inheritance Tax works: thresholds, rules and allowances
Thank you.