
Two thirds of the hassle of filling in the Self Assessment pages could be avoided if the web site made proper use of information ALREADY known to HMRC instead of asking the taxpayer to fill it in over and over again.
As an absolute minimum, that means:
a) tax returns for previous years remaining viewable for the statutory SIX years
b) ability to automatically COPY last year's answer as default in all questions where the answer is still likely to be correct (eg employer's name, bank account number, etc)
c) Not asking for information already known to HMRC. Use the information submitted by the third party (UK bank interest, share dividents, wages, pensions etc) and ask for confirmation that the values are correct instead of entering them from scratch).
d) Already know about, and *USE*, details of my overpayments and overpayments. You should be TELLING me about them, not asking me to tell you what you already should know.