HMRC is sending out letters with payments to households from this June worth £2,000 each on average according to tax rebate experts. Every year, sends a flurry of correspondence to households across the UK as it readjusts for people's tax situations following the new financial year kicking off.

It invites some people to submit a self-assessment return, it tells others that they underpaid tax and will have their code adjusted, while for others, there's actually some good news in the form of a tax rebate.

This happens when a taxpayer accidentally overpays tax, perhaps because they were put on an emergency tax code when changing jobs, or made an overpayment due to being eligible for a tax reduction due to circumstances changing. According to tax rebate experts Swift Refunds, the average rebate from HMRC is worth £2,000, though it can go even higher. HMRC says rebate letters will start being sent out this June.

A spokesperson for the firm said: "Figures from show that the average tax rebate is £2,000, and that those who've never applied before could backdate their claim across four years, potentially receiving between £3,000 and £3,400 as a lump sum."

"A lot of people are sitting on hundreds or even thousands of pounds they didn't know they were owed," said Robert Jones, CEO of the tax refund company.

"With holiday prices rising and many families tightening their belts, now's the perfect time to check what you could claim back. It may well fund the break you thought you couldn't afford this year."

"A lot of people don't realise they may have overpaid tax and, in many cases, they can claim back up to four years' worth in one go," Robert added.

"We regularly see people who've changed jobs, been on the wrong tax code, or had work-related expenses they didn't claim for. These are all common reasons for overpayment.

"To check if you're owed anything, you'll usually need your National Insurance number and a record of your income or employment history. Claims can be made directly through HMRC or with the help of a tax specialist, and the process typically takes a few weeks.

"It's money people are legally entitled to and, for many, it arrives at just the right time."

HMRC says about its tax calculation letters (P800s) and how they determine refunds: "If you've paid too much or too little tax by the end of the tax year (April 5), HM Revenue and Customs (HMRC) will send you either: a tax calculation letter (also known as a P800); a Simple Assessment letter.

"This will tell you how to get a refund or pay tax you owe. The letters are sent out between June and March of the following tax year.

"If your tax calculation letter (P800) says you're due a refund. Your tax calculation letter (also known as a P800) will tell you how you can get your refund.

"If your tax calculation letter says you can claim online, you can claim using the online bank transfer service or request a cheque online. You'll need: the reference number from your P800 letter, your National Insurance number. If you want your refund through a bank transfer, you'll need to have a UK bank account."

But if you did not receive a tax refund letter yet, you may still be due one, and you can contact HMRC to initiate a claim.