Tax on grandchild’s savings

I have opened building society accounts for my 4 grandchildren. I’m named with them as trustee. I know that if interest is over £100 it is potentially liable to tax but my understanding is that only parents would actually be liable. Grandparents are exempt even though I’ve already used up my £1000 personal savings interest allowance. My query is how to ensure I’m not taxed on this. Tried hmrc helpline. 2 reps on the phone didn’t know for sure then I got cut off after 30 minutes. Tried hmrc web chat and again the chat was ended before I got an answer. The reps thought it was up to the building society. Spoke to building society and they said it was between me and the tax man. They don’t ask what relationship I have to the child so don’t know how they could differentiate anyway. Anyone know? Do I have to self assess for tax? Do I just query it when I get a tax code? Any help would be appreciate

Hi ,
 

Please refer to : Interest on savings for children    .

Thank you .