Estate monies

As administrator for my late aunt's estate I have placed estate assets in my name with NS&I, which pays interest on the account and as a safeguard, is government backed should any banks go under. All the monies are due to be distributed shortly to the beneficiaries. How do I prevent having my personal tax code changed at the end of the financial year as these estate assets are not mine? Any tax on the interest on estate monies should be equally shared/paid by the benefactors, not me, but they will be paid out in the next month or so.

Hi Julie Davison,
You would need to write to HMRC, to advise them of the interest that applies to the estate, so that it is not carried forward to future tax codes.  
The address is H M Revenue and Customs Pay As You Earn BX9 1AS.
Thank you. 

Many thanks for confirmation of the address. I am sure this is the address I have already written to a few weeks ago but I will send a copy of my letter again to the address you have stated above, just in case I sent it somewhere else. Most appreciated.