They used to get me to do a breakdown, took me fooking ages first year, then set accounting software up to make it easier, but still needed some time i didnt have to add it all up.
Summer is my busy period, renewal due 1st sept, so i ****** it off, if you dont give it them, they will still renew.
There is a tierd structure, so unless your turnover has shot up, tell to **** off and pay your normal rate, although mine went up 25 quid this year, but as i am always late renewing, i just went with it.