Immigrationboards.com

Hi everyone
I am applying for British naturalisation and I am confused about some topics.
1- referee - if both referee can be British?
2- topic 1.49 page 10 Form AN - address of tax office or tax office reference, I am self employed and I can’t find this answer anywhere.
I would be very grateful if someone here could help me.
Thank you.

1. Yes they can and they must both be over 25 years of age and both be of good character.

2. Your UTR??

I’m trying to sort it out but nobody knows if is the UTR the correct tax address.