This is something you need to use every year in the UK if your salary/income exceeds a certain level (or if the tax man tells you to).
Its a fairly clunky system. There has been minimal UX work. You only find out that amounts of zero can’t be submitted on amount fields after a page is saved.
Company names are limited to about 20 characters. I was transferred between legal entities (same company) during this tax period. The problem is I can’t enter either legal entity name in full, and the difference between them is at the end.
It is worth perservering with as you may get a tax refund.
The use of google authenticator is better than a previous security system that required having a code sent by snail mail in a tamperproof printed format.
Developer Rants 