client on IS as single parent not in receipt CTC included in IS claim, wants to add partner to claim, she is actually unfit for work too but never claimed under these rules in receipt HRM DLA too.
Has been told can't have joint claim for IS only option ESA or JSA.
If she claimed as unfit for work and put partner on claim could they have joint claim for IS?

thanks

Is she currently claiming as single but actually has a partner?

partner not moved in yet he lives with his parents

In CIS/2699/2001 it was accepted that backdated medical evidence could give rise to the disability premium

Is there anything to stop your client obtaining medical evidence of incapacity before October 2008. It may well not make any difference to her award given that she already gets DLA, but it will be a material fact that is grounds for supersession.

The superession may result in the same award, but there will be two grounds of entitlement that are satisfied.

In CIS/4434/2004 Mr Commissioner Mesher as he then was held that of itself the mere determination that a claimant had acquired a partner was not sufficient grounds for a superseding decision to terminate and award of IS, and that the decision maker must take all the circumstances into account before coming to the outcome decision.

This means that in your clients case, if the bacakdated medical evidence is produced before her new partner joins her household, the decision maker would not have grounds to terminate her award and so she will remain entitled to IS on grounds of incapacity