Almost 1000 residents in Bishopbriggs, East Dunbartonshire, may have paid too much council tax for the past 20 years due to an error with valuation bands.
There are concerns that 994 houses in the Bishopbriggs South area may have been put in Band E instead of Band D when council tax was introduced in 1993.
If householders successfully challenge their banding they could each receive up to £5000 and the council will lose up to £275,000 in revenue every year.
Bishopbriggs Community Council treasurer Gavin Owen, who has lived in the area since 1985, said: "This has been going on for months and the council were not attempting to contact individual households."
The possible mistake was uncovered after an increase in the number of appeals over bandings in the area.
Handling the bandings is the responsibility of the assessor for the Dunbartonshire and Argyll & Bute Valuation Joint Board.
The houses affected will be included in a review.
In a joint statement, the Assessor for the Dumbartonshire and Argyll & Bute Valuation Joint Board and East Dumbartonshire Council said former residents might also be affected.