Good question. I've never been able to operate with just one book as Self Assessment material. As SA is an HMRC system rather than a tax, such a book could be very useful in the absence of the 'HMRC Self Assessment Tax Returns Guide'. This Guide was issued to agents from 1997 to 2010 and was a collection of all or most of the SA Helpsheets. I'd say it was the material I referred to most during those years. Some commercial software incorporated these Helpsheets during that time, and (particularly with broadband internet) the contents of this 'bible' became easily accessible via the Revenue site.
Of course, they still are; so if I was starting now, I'd have the basic notes open and then print out, and make notes on the Helpsheets as you prepare each Return. Perhaps file those printouts with the relevant client because, as likely as not, you will need to refer to them next year.
I'd be interested in others answers because I have always had 'Bloomsbury Tax Rates and Tables' by my side and 'FL Memo Tax' each year amongst other books.
