Hundreds of thousands of Brits are being urged to see if they are in line for council tax repayments - with a total of £150million to claim.
Research by Martin Lewis's MoneySavingExpert found that 862,000 people are due a refund for council tax overpayments.
The main reason is that households have moved, but paid their yearly council tax bill in advance.
Their old council can then struggle to track them down to give them their money back.
Another big reason for being owed council tax is because a resident set up payments by direct debit and forgot to cancel them when moving house.
However, MoneySavingExpert said setting up a direct debit to pay council tax was still a good idea as it cuts the chances of you accidentally overpaying.
How to check if you're due a council tax refund
Checking if you are owed cash, and reclaiming it, varies according to your council.
You can contact your council by telephone, email or internet live chat.
You can find your local council's contact details by visiting Gov.uk.
If you're lucky, your council may have an easy council tax refund form to fill out.
Thirty-four councils owe more than £1million, according to the MoneySavingExpert research.
The region with the most cash owed in council tax refunds is London, with £40million sitting in council coffers. After London is the South East, with £27.4million due.
MoneySavingExpert deputy editor Gareth Shaw said: "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."
Last month The Mirror reported that thousands of households have been told to pay back a £150 council tax rebate after they were sent the cash in error.
Residents in North Lincolnshire who live in council tax band E properties were sent the money by mistake.
The £150 government rebate is only for those who live in council tax bands A to D - although you may be eligible for support through a separate discretionary fund.
A spokesperson from North Lincolnshire council said: "Due to a processing error a number of households in Band E properties not eligible for the £150 energy rebate received it.
"We have contacted these people directly to explain the situation, detail how the money is to be recovered and apologise for any inconvenience caused."
