Workers and pensioners are being warned to double-check their tax codes or face being landed with shock bills that they cannot appeal.
More than 20 million codes, which tell you how much of your income will be tax-free, are sent to 16 million people at this time of year.
But already Money Mail has seen several cases where the code - a combination of letters and numbers - is wrong.
Mistakes typically occur when someone has several sources of income or where they have received a large one-off boost, such as a dividend payment, in the previous year.
This can leave someone paying too much or too little tax in future years. The problem is compounded because a rule that allows taxpayers to fight unfair bills is being quietly thrown out by HM Revenue & Customs, we can reveal.
Tax bosses want to overhaul a special concession used by hundreds of thousands of people each year to contest debts they believe have been caused by mistakes at HMRC.
The new rules make taxpayers themselves directly responsible for checking their code is correct and spotting mistakes. If they fail to do this, their appeal will not be upheld.
This will make it all but impossible to claim, since the vast majority rely on their employer or pension provider to take care of tax matters.

There is something very wrong with the government and politicians in this country. They are taking away from the most vulnerable members of society at an alarming rate ( pensioners, disabled, genuinely unemployed ), while at the same time giving the real culprits plenty of time to escape the through the loopholes.

Rotten to the core.

Treasury minister David Gauke said: ‘The publication of these names sends a clear signal that cheating on tax is wrong and reassures people who pay their taxes – the vast majority – that there are consequences for those who refuse to tell HMRC about their full liability.’
When asked why no large corporations were on the list, Mr Gauke said HMRC was taking action to close legal loopholes, and those who prompted aggressive tax avoidance schemes were also being exposed.

Something stinks about all this. I fail to see the difference between tax 'evasion' and tax 'avoidance', but clearly this government does.

Politics in this country has become very nasty, dishonest, deceitful, hypocritical, and undemocratic. Those who have power and influence forget that they are there to REPRESENT and SERVE the ELECTORATE. And once in power these people totally disregard the electorate disregarded and simply regard the ordinary people as a cash cow and slaves to the political elite. Their whole behaviour becomes more akin to Marxist politicos every day.

I will never vote Labour or Tory again. I would like to see how Nigel would fare but I just can't see it - yet

I have been trying to get a tax rebate since October. They're quick enough to take your money but oh, so slow when it comes to paying it back