4. Severe disablement allowance
Severe disablement allowance (SDA) was abolished for new claimants from 6.4.01 onwards, so the information here applies only to people entitled to it before that date.
SDA overlaps with state pension. If your state pension is lower than SDA, your state pension can be topped up to your full SDA entitlement, including any age-related addition. On the other hand, you can put off claiming state pension and keep your tax-free SDA; if you would be due to pay tax on your state pension, you may be better off doing that in some situations even if your pension is a bit higher than your SDA.
There is more information about SDA in Chapter 15, Disability Rights Handbook, 25th edition.