52 year old man, who is registered blind and on long term (non means tested) incapacity benefit of £96 per week, lives alone and only other income is DLA, which includes middle rate care - no one claims carer's allowance. He should therefore qualify for additional means tested income due to severe disability premium.
Is he entitled to income support in addition to (non means tested) incapacity benefit, or would he lose incapacity benefit and move to ESA? If so, is there any way he can keep his incapacity benefit and receive a means tested top up as well?

He would appear to have been losing out on his entitlement ever since the award of the DLA care component. Assuming that he has not got savings over £16000, he is entitled to I/S.

He, or someone on his behalf, should be using the claim line number 0800055 66 88 to claim I/S, asking that the claim to include the diabilty premium and the severe disability premium. He cannot lose his entitlement to Incapacity Benefit, which is his by virtue of his having "purchased" it with a fully paid up NI record: in practice he will merely be receiving a top up of I/S.

Assuming that he is claiming HB/CTB, then the local Authority HB/CDTB section computer programme should have flagged up that, according to the details he had given them, he was actually "underneeds" - ie, not receiving all the benefits he was entitled to and, at the very least, should have notified him of this. Given his disability, we would have gone further and made arrangements to visit him, obviously with a view to helping him make the claim. The overall effect will be an approximate increase in income of about 30%.

Thank you for your very helpful reply. Would he be able to claim any backdated Income Support? Also he has a son at university - if the son came home in the holidays, would this alter the severe disability premium entitlement or would the presence of a student be ignored?

(Fortunately, the underpayment is not from the start of the DLA award, as previously did not qualify, as was receiving other benefits which stopped when son took a job before university. The local authority failed to flag the IS entitlement because they incorrectly removed the severe disability premium)