Is tax credit paid in advance or arrears?

[aftersomeadvice23]

Need to make a change to my tax credits which will affect how much i receive. Does anyone know if it is laid in advance or arrears?
Thanks

It's worked out over the year so if for example you reported a significant rise or drop in income then your payments would just be adjusted over the year. I know that probably doesn't really answer the question !

The theory is that it is paid according to what you earn the same year. Which if you have variable earnings is a pain in the arse. I used to write them a letter every month telling them how much I earnt, so mine was being continually adjusted.

If its a change in childcare does does that make any difference?