Forgot to attach supporting doc of self assessment.

Hi officer, I submitted my self assessment in 2 weeks ago. Statement was issued already. I found that I forgot to attach doc. So just wondering how can I attach/upload those supporting doc (e.g. payment receipt) now? Thanks SL

Hi,
 

You would not need to attach this to the return. You should keep these documents as we may ask for them in the future if we are reviewing your submissions . Thank you.