This valuable relief is worth knowing about. It effectively extends the right to claim OVERPAYMENT RELIEF to cover tax overpaid where ordinarily the deadline of four years after the end of the tax year concerned has not been met. It can only apply if specific conditions are met. In particular you have to show that it would be unconscionable to seek to recover the amount, or to withhold repayment of it if already paid, and also your tax affairs have to be otherwise up to date or arrangements have been put in place to bring them up to date so far as possible. Recent case law gives more ammunition to claim special relief in certain circumstances.