Exeter Racecourse general manager Jack Parkinson said: “We rely heavily on the bookmakers.
“If their profits are hit by this new tax, then that will have a direct impact on the racecourse through the levy, which is where the money goes; and then through that we get given prize money and sponsorship and all those aspects of it.
“The bookmakers will just cut down on that, so the prize money will lower, which will mean less horses in racing and, ultimately, will have a huge impact on the small courses like Exeter.
HM Treasury said: “We do not comment on speculation around future changes to tax policy.”