NCMA (as they were) and HMRC came to a special agreement many years ago about childminder expenses. The agreed percentages are generally considered to be very generous. They are detailed in resources on the Childminding Forum here - and on the HMRC website here.
SOME childminders choose not to use these agreed expenses - they use an accountant and they calculate expenses in a different way - that is fine if that is what you want to do but you cannot pick and choose the ways you do your accounts.
You EITHER use the agreed expenses in the links above OR you use normal self-employed expenses. You need to work out the best way for you.
You can find more information in this HMRC webinar.
I have also written this guidance document with support from HMRC and an accountant.
At the end of the day your accounts are between you and HMRC – however, the Independent Childminders Facebook group cannot be held responsible for childminders following incorrect advice and being pulled up for doing it wrong if they are audited by HMRC.