......or earn into the top tax band.
.......
This used to apply to me when I helped make cough sweets! I could never understand why I'd to fill the bugger in when I was PAYE though, even the local tax office talked themselves into a hole trying to justify themselves. When Cadbury took over & my tax office moved to Brum they said I no longer needed to fill 1 in. Presumably it depends how your tax office interprets the rules. :-/
Putting beanz in tinz doesn't pay well enough (contrary to local belief ) to worry aboout 40% tax
The problem is, everything else that's taxed automatically is done at the basic rate, so although your salary will have been taxed correctly through PAYE, your bank / building society interest, any share dividends, etc. etc. wouldn't. In most cases the difference is pennies, of course, and they work this out after a few tax returns and adjust your tax code to compensate.
I pay someone to do mine as I can't be bothered
Quite often someone experienced will find plenty of ways to save you money too, so the overall cost of employing someone to do it may be negative. For example, do business miles in a 3.2 Omega and you can claim a tax rebate on much more than the the paltry amount of mileage allowance your company will give you.
Kevin