On 20th Sept 2011 I recieved change of codings because I started drawing a small pension (I was already drawing another pension) and I had also changed jobs, in Feb 2013 I received a P800 saying I owed approx £3800 from year 2011-12 tax so I have been disputing this saying they had all my correct details etc etc. They are now saying under ESC19A I have no recourse but I decided to ask for all my data as I was certain I had contacted them, on one of the forms I found that they issued change of codes on my pay main pay and my main pension on Sept 2011 which in effect caused them to under tax me ie changed pension from D0 to 65L, now I know your going to say 'but its up to you to ensure your paying the correct tax' and I would agree to a point but I then found that I had rang them 9 days later to ask them how codes were worked out and were the new codes correct, I also told them my expected total pay for that year and I overstated my pay to be on the safe side but the biggest evidence against HMRC is that the person I was speaking to stated that the codes were correct,see the statement below on their paperwork- TP called to ask about codes and how they are worked out, took estimated income and codes correct (this is there exact wording) The thing is since I took my main pension(2006)they have every year to date messed up my codes and I have had to pay back underpaid tax so this was the last straw. I know they have informed me within the time limit but it is up to HMRC to issue the correct codes, If I then have reasonable belief that my codes are correct ie I did contact them and they said there were correct when in fact they were not I believe I have a case against them.Do you think I have a case here.