Aviva Premiership club London Welsh have lost their appeal against a five-point deduction and £15,0000 fine for fielding an ineligible player in this season's competition.
A further five-point penalty, though, that was suspended until the end of next season has been removed, the Rugby Football Union announced.
The independent appeal panel's decision means London Welsh are five points adrift at the Premiership basement of 11th-placed Sale Sharks with just four league games left.
The club's appeal hearing was held in London last Thursday.
A panel of inquiry's initial punishment was for Welsh fielding an ineligible player - scrum-half Tyson Keats - in 10 Premiership games this season.
Mike Scott, the former London Welsh team manager, has been banned for life from rugby after he admitted supplying false information regarding New Zealander Keats, including a forged passport, to the RFU.
Keats was eligible for an ancestry visa, due to his grandfather being born in England, but Scott made a mistake in the original application.
Instead of reapplying, Scott told Keats' agent and the club that the visa had been successfully granted to the player.
Meanwhile, Scott submitted false documents to the RFU in a bid to pass Keats off as English-qualified. Scott accepted a police caution on February 14 for his actions in falsifying registration documents.
London Welsh, though, argued they should not be blamed for fraudulent behaviour conducted by Scott, who was described in the original judgement as a "rogue employee".
The appeal panel, meanwhile, confirmed today that the £15,000 is to be paid within 21 days.
Panel chairman Gareth Rees QC said: "The independent appeal panel accepts that the circumstances of this case are quite exceptional.
"However, we have to mark this serious breach with a points deduction and, although we have allowed the appeal in respect of the five points which were suspended, we must acknowledge the impact on the integrity of the game and deduct five Premiership points with immediate effect."
According to Premiership regulations 14.2 (c), the decision is final and binding.
The appeal panel's detailed written judgement concluded by outlining its findings.
The panel said: "In our judgement this was a serious case which must be met by a points deduction.
"It was particularly serious because it had carried on for a very long period of time.
"We emphasise again that the question of proportionality remained central to our deliberations throughout.
"We identified the following aggravating features: failure to have more than one person checking the club's system for player registration; that it covered 10 matches when the club was able to select its first choice scrum-half when he was ineligible; the signing of blank forms by players who should check the details included in all cases.
"We identified the following mitigating factors: the conduct of MS (Mike Scott) could not have been predicted; the club coach responsible for selection had no knowledge that the player was not eligible; the club's attempt to remedy the situation when it became clear what had happened."
The panel said it considered whether it was possible to suspend all, or any, of the five points.
"We decided that it was not because these were such serious breaches that had to attract an immediate points deduction," the judgement continued.
"In our judgement it was only the exceptional background circumstances that could lead to a points deduction outside the normal range.
"We are of course aware of the potential impact this decision may have, but we cannot do more than take that into account in our general assessment of the overall situation that persisted for so long."
London Welsh, who are in their first season as a Premiership club, continue their league campaign at Bath on Saturday, before hosting Northampton on April 14 then visiting London Irish and entertaining Worcester on May 4.