tax credits, self employed and hours

[mafog]

If you are self employed, how do you work your hours out for tax credit purposes. Especially if they vary week to week. Just discovered that there is quite a differentce between 0-15 hours and 16+ with regards to what we would receive.

I took advice from my father on this one....He said he has always put full time hours as with self employment you are never really off duty as it were so just say 38, they won't question it.
He was apparently advised to do this by someone who deals with tax credits and has never had any problems, neither have I.

wow needed some punctuation, hope it makes sense.

My hubby is self-employed and we decalre 40 hours, it is really hard to predict as some weeks he works 70 and other weeks 10 but I guess it averages out over the year. I tend to overestimate his income for tax credits- would rather get an addtional payment at end of year than have to pay back