Centre Rohan Janse van Rensburg has been fined £32,500 and handed a two-week ban for signing contracts with Premiership clubs Sale and Gloucester.
Van Rensburg signed a three-year deal with Sale for 2018-19 onwards, having already agreed a similar-length deal with Gloucester and been paid £25,000.
He followed through with his move to Sale, who have been handed a five-point deduction, suspended for two seasons.
Sale were fined £20,000 for breaching rules about approaches to players.
Matthew Ginvert, the agent representing the 25-year-old South African centre when the first of two contracts with Sale was signed on 11 January 2018, has been reprimanded, fined £3,750 and directed to undertake the agent's education programme.
All three parties accepted their respective charges and have the right to appeal.
The judgement handed down by the independent disciplinary panel, made up of James Dingemans, Tim Ward QC and Gareth Graham, said that the fine imposed on Van Rensburg would be paid to the Rugby Football Union, with £25,000 passed on to Gloucester to recover the advance they made to the player.
The timing of the player's two-week suspension will be confirmed once the season calendar is confirmed, as all competitions are on hold during the coronavirus pandemic.
While Sale were fined, they were not ordered to compensate Gloucester, who were seeking more than £400,000 from their rivals.
The disciplinary panel concluded that they did not have "sufficient information to make an award which would be fair to both Gloucester and Sale".
It was added that damages could be sought in the High Court, with Gloucester saying they are considering their position "in relation to legal proceedings to recover compensation".