CCM14335 - Closing the Enquiry: Time limits for penalties
Paragraph 6 of Schedule 2 of the Tax Credits Act 2002 provides time limits for penalties. The time limit for penalties is the later of:-
a. one year after the end of the period during which you could have made an enquiry (the date the enquiry window would have closed) and
b. the end of the period of one year beginning with the day on which the S19 enquiry is completed.
Some examples of time limits for penalties can be found at CCM14336.