I have a case of a couple, he is subject to immigration control and works 16 hours plus.

She is a U.K citizen and doesn't work

They have a child so clearly need to submit a tax credit claim, but would they get WTC?

I know that, if she worked, she could claim and get the couples element. It is also clear that you can claim WTC if you, or your partner works full-time. However, in this case he wouldn't be able to get WTC if he were the claimant.

However, what worries me is that it appears from my handbook that they would not be able to get WTC if he were a citizen subject to immigration control for WTC but not CTC. Examples of this would be citizen's of Algeria and Morroco, who have a treaty areement with the EC covering this, but who (unlike Turkey) are not covered by the European Convention of Social and Medical Assistance.t

Is this right or am I misreading it?

If it's right it seems mad as it's effectively penalising you for having, what is supposed to be a concession in your favour.

I'm a bit confused by my current CPAG Handbook page 1386 which says that she can claim and they will be entitled to the second adult element

I would have hoped that this covers it in the HMRC manual:

TCTM02106 - Entitlement: Immigration rules
The treatment of family members
The Tax Credits (Immigration) Regulations 2003, Reg. 3(2) and (3)

Provided one member of a couple is not subject to immigration control, or is covered by one of the exceptions to the general exclusion, or is benefiting from the transitional rules, the couple is entitled to CTC or WTC (or both) as though:

neither of them were subject to immigration control (as if the other partner were not subject to immigration control)