There are strict time limits on when an enquiry into
someone’s tax credit entitlement can be opened. These time
limits are usually referred to as the ‘enquiry window’.
An enquiry cannot be started:
Once the enquiry has been started there is no statutory
restriction on the length of time it can last, but the claimant has
the right to ask us to close the enquiry, see
CCM17090.
You can find more detailed guidance regarding the enquiry
window at
CCM12020. Details of the enquiry windows
when there have been multiple awards are at
CCM12090 and
CCM12095.