If you think your self-assessed income is going to be significantly greater in the following year, are you bound to tell the IR and then pay more on account?
I would say if it is the first year it is going to rise a lot then No, what they will do is assess your next tax return they will then ask for payment on account, but you do not have to pay that, but the down side to that is, that if it rises again you will be charged interest on the outstanding tax, thats what they told me last year anyway. hope I have explained it clearly enough, hard to put into words. Ray