My client was working and in receipt of WTC. He has been made redundant and has received three months pay in lieu of notice. He will not be required to work during his notice period.

Can he continue to get WTC until his notice period ends?

I've always understood that pay in lieu of notice is in effect compensation for breach of the employment contract by the employer. In other words, he should have been given 3 months notice to terminate his employment, but the employer failed to do this. It follows that his employment has ended. Common sense would say that he therefore cannot get WTC, (but I hesitate to suggest that common sense is used in framing Tax Credit regulations!). I look forward to someone who knows the regs. proving me wrong.
(Incidentally, if he was on gardening leave and therefore still employed until the 3 months was up, I would be saying that WTC should be payable.)