How are savings in a joint account treated for Income Support/Jsa? I'm thinking particularly of same-sex couples who have a joint account, but where only one partner's income and savings would be taken into account. Are the savings simply halved, or treated as belonging entirely to the claimant?

Given that two people in a same sex couple are not treated as either a married or unmarried couple for IS purposes, I think that the savings would come under reg 52 of the IS (General) regs 1987:

Capital jointly held

52. Except where a claimant possesses capital which is disregarded under regulation 51 (4) (notional capital), where a claimant and one or more persons are beneficially entitled in possession to any capital asset they shall be treated as if each of them were entitled in possession to the whole beneficial interest therein in an equal share and the foregoing provisions of this Chapter shall apply for the purposes of calculating the amount of capital which the claimant is treated as posessing as if it were actual capital which the claimant does possess.

Whoever wrote this obviously didn't believe in short sentences. You might want to read the comments on the reg in Bonner