Hi, I have come across a situation where an asylum seeker (no decision on application) is married to a British Citizen, and they currently reside in a mortgaged property.

The asylum seeker receives no NASS support (neither accommodation or income) and has no recourse to public funds. Would the British Citizen qualify for any single person discount / second adult rebate / anything else ... or would full council tax be liable for the couple?

I will try to answer this but others may have other points to add. There is no entitlement to a discount because there are two occupiers, unless one or other person falls within a category which means they can be "disregarded" for the purposes of assessing the discount (such as a F/T student or severely mentally impaired, for example).

There cannot be second adult rebate because a person's partner cannot be a "second adult" in this context.

However I think the British citizen ought to be able to claim Council Tax Benefit in respect of the couple, although whether that is successful will obviously depend on their financial circumstances.