Is it better to over estimate or under estimate your income?

[Butterpie]

Just sorting out tax, tax credits, hb and so on now I am self employed. My income could vary wildly so I would rather be a bit worse off each week if it means I won't get a bill at the end of the year it that makes sense.

So, do I err slightly high or slightly low? My income could be anything between 0 and £250 a week, rough calculations put me at about £105 a week profit, but that is really a guess as it is two businesses that are both very variable.

if they give you too much at the end of the year they will demand it back or take it off your next years money so i would have thought if you can manage i would over estimate your income that way you wont get caught out with a big bill at the end and they do pay you any monies owing when you give them the exact figure which would be a nice bonus or treat for you. however go can inform them at anytime if your income has changed and they will adjust your payments so you have to do whats best for your situation.