I haven't paid tax - what should I do?

Personally I would keep my mouth shut and wait for them to speak to you. Its up to them to chase you, not the other way around If you listen to random people like Fairfax, who have an opinion and no proof you will end up paying lots of money. According to the HMRC website: "The onus of proof is usually on the appellant. For example, if an appeal is against a Revenue assessment or amendment the appellant has to prove that the amendment or assessment is excessive. If the appellant cannot prove, on the balance of probabilities, that an assessment or amendment is excessive, the assessment must stand good". So you would have to prove whatever decision HMRC made about the tax that you owe if you disagreed with it, but the HMRC website also says: "Where, however, an appeal is against a penalty, for example a tax geared penalty for making an incorrect return from applying and the onus of proof is on HMRC to show that the offence has been committed. In the case of a fixed penalty for a failure to, for example, submit a return, HMRC must put forward evidence of the failure. The appellant can either give evidence to show there was no failure or offer a reasonable excuse for the failure. Where an assessment is made for the purpose of making good a loss of tax attributable to the appellant’s fraudulent or negligent conduct the onus is on HMRC to show fraudulent or negligent conduct by the taxpayer and a loss of tax attributable to it." So HMRC would have to prove that you have committed an offence or the tax return you submitted was incorrect on a purpose.

It is better to be honest and to sort it out properly. Firstly find a good accountant to back you up with this and then talk to the HMRC. Try a local office face to face in the first instance rather than the phone. They will pursue you for the money, but a good accountant will bring that down as low as possible and usually an amount can be agreed at some stage.

In these circumstances, "Anon" is probably about right. Whilst it is your responsibility to declare your earnings, there is no chance at all that HMRC will be looking for you, and there is certainly no criminal activity here that could see you end up in court. Look at the facts: you say a few years ago, so there is every likelihood that they would have approached you before now. You thought you were an employee, and you were were paid an hourly rate - just like an employee. Employees pay tax under PAYE. If your employer didn't do this, that is his responsibility, not yours. You were working abroad for a couple of years. If you were out of the UK for a full tax year (April to April) under the same contract, then you will have no UK tax liability anyway. You don't really have too much to worry about.

It depends on which country you worked in and if you should be regarded as non resident for that period. The N I is voluntary - but it's your pension that is being hurt if you do not pay. You need to write a letter to HMRC. Give your name, national insurance number etc , say what has happened and ask for advice. A technician wil write back (or phone if you give a phone number) and start to sort out. It is complicated by residency and dual taxation. If thee is a bill you can have up to three years to pay it back,

Call an accountant and ask them to sort out your books.