If I read Abbotyobs's starting post #1 correctly, he is talking about back-tax for 2010-11 arising from an incorrect coding. That would probably rule out the operation of ESC A19, but bits of the following for what it's worth, would seem to apply generally to some of the replies on this thread. Apols. for the long post, but it's not a subject you can easily deal with in three lines.
From my recent personal experience of getting a little old lady's shock £2500 back-tax bill waived for her ** I can recommend googling the five letters - LITRG. This takes you to the non-commercial website of the Low Incomes Tax Reform Group – set up altruistically by the Chartered Institute of Taxation
In brief, they set out the whole back-tax under-deduction story and provide you with the self-service tools for the whole remedy, where it is appropriate. It doesn't matter if you are not actually "Low Income" – in this case deemed to be about < £17k. There is a lot of less helpful stuff and feeble chat-nets on the subject elsewhere on the internet. LITRG is tops for PAYE back-tax bills, especially if you can support your letter with your records.
Whatever else may have occurred, in order for ESC A19 to operate successfully, it helps if you are on PAYE (and you are not submitting, or not being required to submit annual tax returns) and it helps if the back tax is not being claimed off you (for the first time) until more than about 12 months after the end of the tax year involved – and that HMRC have made a mistake, such as having the info and not using it. My understanding is that this situation can arise for anyone who has been told by HMRC that "You do not have to submit an annual tax return – we will take care of it all for you." That can include higher rate tax payers whose tax-affairs are deemed to be "simple." In essence, it was a failed punt by HMRC to save on staff and paperwork. We all fall for it, because the tax rules have been made increasingly complicated over the years with the endless tinkering.
Having said that, you must be prepared to put a lot of patient reading and work into the problem, and one's willingness to do that will depend on the size of the back-tax bill and whether you have kept all your records (min 6years). Particular tax problems have been created for folks who have started receiving their State OAP in the last few years (men 65 – women 60) because this income has to be taxed off-of some other income. Special treatment was ordered by HMG for this element of the historic miscalculations by HMRC, because in many cases HMRC just forgot what they already knew and didn't tax the OAP. Also the "age related personal allowance" virtually demands that qualifying folks within that income band submit annual tax returns, in order to get it and/or avoid tax fraud.
Further points - Take time to compose the letter – Alumni of the Joint Services Service Writing School will know what I mean. Copy it openly to your MP with a brief explanation. Consider mailing special delivery, then you won't be sitting for six weeks wondering if it has arrived. I personally don't believe in telephoning. If you are faced with a tax investigation – unlikely at this level - get yourself a good accountant, and possibly consider "tax investigation insurance" – available in advance only. And don't offer to take Dave Hartnett out to lunch.
Our old mum firmly believed, and used to beat into us regularly that "If it was Authority – it must be right." Nothing personal, but I would never trust my tax calculation to HMRC. Obtain a good commercial personal tax programme – the one I have used for over 20 years, now costs about £30 each year and allows up to six "family" tax returns each year. You can take your time. You don't have to submit a tax return if it's not required, but whether your tax is right or wrong, you cannot be certain either way unless you have calculated it yourself. It is well-nigh impossible these days to calculate it manually.
You can print and send a paper tax return (by October 31st) even if they have told you not to. Its the only reliable way to get your money back. The tax code is only their "best guess" for the "current" tax year. Tax Codes can be changed at any time if your circumstances change or if you become aware of an error. One can only be certain what one's income was, when all the P60s etc. are in. HMRC's annual "reconciliation" provides no certainty, as we have seen in the last two years.
Filing your return on-line from a commercial programme is a doddle and is supposed to be secure – but getting to the position where you can file on-line can take literally months. You have to use the HMRC website to set up or apply for various access codes to be mailed but if you have not already been issued with a UTR – forget it. If they don't want to issue you with a UTR, it seems they will ignore your request - that's a battle to come. Last time I looked, you could not ask for a UTR on-line. They're not all bad though. I found myself having to make an FOI request to HMRC in about 2008. Eventually they came up with the goods – ie my complete tax-records in spades, including for good measure a photocopy of a hand completed RN pay sheet (size about 2ft x 2 ft) for A/S/Lt. LFH at RNAS Culdrose in 1961. Fit for a museum it were.
Many Happy Returns - LFH
PS ** the 3 grand demand was just for two years, but it was over two years late. Also it had been going on for six years (near 7k under-deducted) and it all looked totally under control (even to me) at first glance.