OK, I'll await further details if you want to pass them on and provide below the general answer I received. Hopefully all abbreviations used should be clear. Please note that without full access to the case in question and particularly the figures any advice contained could be just speculation rather than fact.
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The law allows a person 3 months to change their mind about whether to have extra weekly pension or a lump sum, and that can be extended in certain circumstances. However, I'm not sure that the ability to extend covers this scenario. That's because I think the original advice that the lump sum didn't make any difference was probably correct. I'd have thought they were getting State Pension Credit rather than income support if they were both over pension age.
A lump sum of deferred retirement pension is disregarded as capital for SPC for the person's lifetime. I assume that's the same whether it's paid during an award, or before making a claim, but the suggestion seems to be that it's different. I can't see any rule to support that, but I'm not a SPC expert. On that basis I'd have thought the SPC claim ought to succeed, and he'd then be able to get the HB and CTB back. But of course, it all depends how much retirement pension he's entitled to on a weekly basis. I can't help wondering if it's the award of RP that made the difference, not the lump sum. If it's too much, then he might not get SPC. I can't say without more information.
I should point out that if he does manage to change to weekly increments and repay the lump sum, the disregard stops and he might have to pay back HB and CTB that was paid to his wife, because they were a couple and what's his is hers and vice versa.
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