Premiership clubs have unanimously agreed to cut the salary cap by £1.4m.
The senior ceiling will come down to £5m from the 2021-22 season, plus the existing £600,000 of academy credits, to help clubs with the losses incurred as a result of coronavirus.
The reduction will be in place until the end of the 2023-24 season. An announcement is expected on Tuesday.
It is hoped the cap could then return to the current level of £6.4m plus £600,000 academy credits.
Changes have also been agreed to the marquee player dispensation, which will remain as two players' salaries not counting towards the cap for the next two seasons before being cut to just one from the 2022-23 season onwards.
The first Premiership clubs returned today to phase one training, which allows for small groups to train together while observing social distancing.
Harlequins confirmed that five players opted not to return to training, but club bosses say there is "no pressure" and they are confident that the squad size is "sufficient" to carry on without them.
The club's head of medical Mike Lancaster said: "There are a few players who chose to opt out and numerous reasons spanning from that they have excellent home gym facilities and are safer with that; others, because they have people on the vulnerable list, which could be players potentially with pregnant wives or partners."
Asked to give a number for those who had opted out, he said: "At present there are five players."
Premiership Rugby (PRL) announced last week that the season will provisionally resume on 15 August.
Lancaster said the timeframe is "more than adequate" to get players ready for matches, and that there is a particular focus being placed on trying to prevent soft tissue injuries.
Meanwhile Laurie Dalrymple, Harlequins' chief executive, said they were "expecting there could be some hurdles to get round" before the season restarts, and that the schedule would allow for that.
Although the current phase of training means players do not come into close contact, Harlequins has decided that if a player tests positive for coronavirus or develops symptoms the rest of the group they have trained with will isolate for seven days.
Testing is not currently being carried out at club level.
Former England captain Chris Robshaw announced in February he would leave the club at the end of the season, but is currently in training.
It is understood Kyle Sinckler, who is moving to Bristol Bears, will not be part of training.
No timeframe has yet been set for when Premiership clubs will move into phase two, which would allow for contact training.
The expectation is that it will not be for several weeks due to the time needed to improve the fitness of players, work ongoing surrounding testing programmes and the impact on whether clubs would have to take players off the furlough scheme.
On the possible return of fans, Dalrymple said: "We want to be in a position whereby we can have some degree of spectator access into the ground - maybe that could be included within the season's resumption? It may end up waiting until we restart next season."
Domestic rugby will return in New Zealand with full crowds, which he described as a "nice indicator that we are getting back on our feet".