MoneyHMRCNeed to knowAll you need to know as HMRC sends notifications and some recipients must respond or risk missing out on an average £47307:41, 04 Jun 2026HMRC has revealed that nearly one million people are missing out on an average of £473(Image: Getty Images)Hmrc tax refund letters: need to know as millions face missing out on £473 average payoutMillions of households across Britain are set to receive crucial tax refund letters from HMRC starting today, with urgent action required in some cases.The tax authority is dispatching approximately 4 million income tax refund letters between June 1 and August 31, warning recipients they 'must respond' if asked for more details or risk missing out on money owed to them.Shockingly, nearly one million people are missing out on an average of £473 simply because they failed to respond to their letter last year. Officials warned: "Remember getting a letter about a tax refund but didn't do anything about it? Last year, almost 1 million people didn't claim back the money they're owed."The refunds typically arise when people overpay income tax due to incorrect tax codes, job changes, or holding multiple jobs simultaneously. Claiming online via your Personal Tax Account or the HMRC app is the quickest method, with payments usually processed within 5 working days.However, HMRC has issued warnings about fake letters circulating, stating: "You must respond to the letter so we can make any repayments owed to you as soon as possible. If you receive further requests for information to be sent to an email address that does not end in 'hmrc.gov.uk', they will not be genuine."The letters, known as P800s, are being sent to employees on PAYE and pensioners who may have overpaid tax on their income. Those with work-related expenses or complex income arrangements typically need to make claims themselves within four years using the HMRC app or relevant forms on gov.uk.READ THE FULL STORY: HMRC letters landing from Monday to 4m and adds 'you must respond'‌