Households across Britain are due a windfall after it was revealed £150 million is owed in council tax refunds.
Martin Lewis told his followers on Twitter to "check now" if they are eligible for a payout, with 862,000 in line for one.
Households may be owed cash because they paid their council tax bill upfront before moving out of the area.
By contacting your local council, you will be able to find out if you're due a refund.
The Freedom of Information request was submitted in the latter stages of 2021. Dominic Lipinski
By visiting Gov.uk, you will be able to find out the contact details for your local council.
Some councils may require a completed online council tax refund form in order to claim the payment, however you'll be asked to provide eligibility evidence for any backdated claims.
Thirty four councils in England, three in Scotland and one in Wales, each hold council tax overpayments worth more than £1 million, a Freedom of Information (FOI) request from Martin Lewis' MoneySavingExpert revealed.
Money Saving Expert's Martin Lewis has revealed how to check if you are eligible for a payout. Kirsty O'Connor
Birmingham City Council were revealed to be the council with the most arrears, with a £5.4 million quoted.
Households have been urged to check now if they are one of the 862,000 eligible for a payment. Joe Giddens
Gareth Shaw, deputy editor at MoneySavingExpert.com, said: "While many councils do make an effort to track down those who have cash lying unclaimed, they are still staggeringly sitting on £150 million worth of overpayments.
"You're less likely to have overpaid if you use direct debit, but it's not impossible, so if you've moved home it's worth checking if you might be due, especially if you changed local authority area and paid by cash, cheque or standing order instead.
"Each council has its own way of processing claims, but some have an easy online form.
"But don't just call on the off chance you might be due – do a little bit of digging so you don't clog up councils' switchboards for those who need essential and urgent support.
"Check your previous statements and bills to see if council tax you paid upfront covers a period after you moved and if you closed your account in credit."
The FOI from MoneySavingExpert was submitted in the latter stages of 2021, with the last set of figures obtained from councils in February 2022.
Most councils responded to the request with the value of refunds owed at the end of the 2020/21 financial year.