Statistics published by HMRC shows that, in the 2013-2014 period, a huge proportion of decisions reviewed internally by HMRC were either cancelled entirely (in 42% of reviews) or were varied (in 7% of reviews).
Source: HMRC’s Reviews and Appeals – 2013-14
For those that made an appeal to an independent tax tribunal instead of requesting an internal review by HMRC, 6 out of 10 appeals were settled by agreement before reaching the tribunal stage. 44% of these were settled in the tax-payer’s favour. However, of those that did proceed to tribunal, 76.2% were decided in HMRC’s favour.
This enormous level of misjudgement by HMRC suggests that anyone thinking of challenging a HMRC decision themselves stands a good chance of having an assessment reduced or cancelled completely.