The Tories have been probed after accepting donations from a man who had died of asbestos poisoning.
An Electoral Commission investigation found the party had broken the rules by failing to promptly return a £2,000 payment from Worcester philanthropist Cecil Duckworth CBE, who had set up a standing order to support the party.
Mr Duckworth founded both manufacturers Worcester Bosch and Rugby Union team Worcester Warriors.
Mr Duckworth died in November 2020, aged 83, making him an “impermissible donor” under UK election law - but the party kept his donation for more than a month before it was returned.
The Commission found the Tories had broken the rules by returning the cash late, but did not impose a sanction on the party.
A spokesperson said: “We decided not to impose a sanction because we did not consider it proportionate and the party returned the donation after it became aware of the circumstances.”
The Conservative Party did not comment.
The Tories were also fined £3,080 for late reporting of four loans totalling almost £100,000.
The Commission said: "We considered the case in line with our Enforcement Policy and decided that sanctions were appropriate for each misreported loan.
"When deciding the level of sanction, we took into account that, as a result of these instances, the party has improved its systems to reduce the chances of future issues."
