Taxed despite no profit

Hey, I just did my self assessment for the last year, and it was pretty much the same as the year before - I have a full time job (lower tax bracket) and make well below £1k as self-employed. However I still have to pay £14 tax, same as last year, despite my self-empolyed income being less than £100 and the expenses way above that, so no profit as self employed. Is that normal? I also declared my £19 savings interest, despite it being below the threshold. Is anyone able to advise? It's not enough to get an accountant to question it, but I worry I'm missing something.

Hi Holden Caulfield,
You will need to please contact us on webchat for your record to be accessed.
Go to Gov.uk and search 'contact HMRC'.
Then choose Self-Assessment and go to 'Ask HMRC Online'
Self Assessment: general enquiries
Thank you.