Councillors fear firms could close in Sutton Bridge and Long Sutton unless a hike in business rate valuations is reversed.
Couns Chris Brewis and Michael Booth are among those working to bring about revised valuations after business were hit by massive hikes, some seeing bills more than double.
Coun Brewis told the parish council: “It is going to affect businesses to the extent where it is going to affect the viability of these two small towns.”
Coun Booth said the bigger firms were being hit hardest but, if they were to close, smaller ones could follow.
South Holland District Council has been awarded £295,000 for a locally run business rates relief scheme, which should see increases capped at £600 for businesses with a rateable value of £100,000 or less. But that cash will only last for four years.
Rates are normally geared to rents and were set by the Valuation Office Agency.
Coun Brewis said: “There are no rented substantial businesses here, they are all owned. They seem to have been extrapolated on square footage, which is giving a completely false picture.”