Think your tax affairs are settled? You feel you took reasonable care when preparing the original submission and conclude that HMRC is out of time to assess for additional tax. Under this new legislation, because you didn’t correct the error, HMRC could argue that you failed to comply with your obligations. Otherwise, a measure intended to modernise compliance could undermine it – if by reviewing your old tax affairs and finding a historic error, you risk a dispute with HMRC and a penalty for not reporting it, why do it at all? Fiona Fernie is a partner at leading audit, tax and business advisory firm, Blick Rothenberg