“(2) Where a decision under section 10 is made on the ground that there has been, or it is anticipated that there will be, a relevant change of circumstances since the decision was made, the decision under section 10 shall take effect— … (c) where the decision is not advantageous to the claimant— … (ii) in the case of a disability benefit decision […], where the Secretary of State is satisfied that in relation to a disability determination embodied in or necessary to the disability benefit decision […], the claimant or payee failed to notify an appropriate office of a change of circumstances which regulations under the [Social Security Administration Act 1992 ] required him to notify, and the claimant or payee, as the case may be, knew or could reasonably have known that the change of circumstances should have been notified, (aa) from the date on which the claimant or payee, as the case may be, ought to have notified the change of circumstances, or (bb) if more than one change has taken place between the date from which the decision to be superseded took effect and the date of the superseding decision, from the date on which the first change ought to have been notified, or (iii) in any other case, except in the case of a decision which supersedes a disability benefit decision […], from the date of the change.”
“(iv) in the case of a disability benefit decision, where the change of circumstances is not in relation to the disability determination embodied in or necessary to the disability benefit decision, from the date of the change; or (v) in any other case, except in the case of a decision which supersedes a disability benefit decision, from the date of the change.”