Working part time due to illness?? What benefits?

[ledkr]

My son is 26 and has end stage kidney failure. He is still working full time and is on the transplant list. We haven't claimed dla yet as probably wont get it until he starts dialysis which he could now but Dr is happy for him to hold off as he doesn't feel too bad.
He has been under pressure from work to decrease his hours due to his illness and will probably have to soon. He could be signed off now but he wants to keep working as he enjoys it.
We have been told different things by agencies. Law centre said he can get tax credits to top up his income then tax credits helpline said only if getting dla.
Who is right?
It seems a shame when you are trying to keep working but get penalized.

Here he needs to be claiming DLA, and working at least 16 hours per week. Less than that and I think he would need to claim ESA.

Thanks I think that's right I'll do forms tonight been a bit unmotivated as don't think he will get it. Bad really cos many must be too ill to work full time but not get dla