England's elite players "can't be expected" to play 12 consecutive months of rugby when the season resumes in August, says head coach Eddie Jones.
The Premiership is scheduled to restart next month, with nine rounds still to be completed as well as the Champions Cup knockout stages.
International fixtures will follow, before the prospective start of the 2020-21 domestic campaign in November.
"I think it's going to be difficult," Jones told the BBC.
"We are going to have to have a lot of consultation between the national union and the clubs on how we look after the players."
With talks over a global calendar stalling, the Premiership clubs plan to run next season from November to June, before the British and Irish Lions tour of South Africa which has been confirmed for July and August.
"We can't expect the players to play this season, play internationals and then go straight into another club season, and then potentially go on a Lions tour," Jones continued.
"It's a job for the administrators to work out how to find the right balance."
The England boss warned this prospective schedule could mean players miss "two pre-seasons in a row" which would be highly detrimental to their conditioning.
"The game needs our players to be at their absolute best - that's what people want to see," Jones said.
"To have your best players playing against each other at their best, they need to have a proper regeneration period post the season, and then a proper pre-season - a six-week period, at least, of good strength and conditioning and base training."
The conflict between the international and domestic game is at the heart of the impasse over a new global calendar, with French and English clubs resisting attempts to revamp the schedule.
"It's a matter of working out what is an absolutely vital [number of weeks] for a training period, and then working out how many [weeks] the internationals are going to take and how many the clubs are going to take," Jones added.
"It seems like a straightforward situation, but we know it is complicated and difficult. We would all like to come to a solution."
'Delight' at Tuilagi decision
Meanwhile, Jones was "delighted" by England centre Manu Tuilagi's decision to remain in the Premiership after completing a move from Leicester to Sale on Monday.
The 29-year-old would have made himself unavailable for England selection had he moved overseas, but Jones says he gave the Samoa-born centre "a small piece of advice".
Jones explained: "Manu made up his mind what he was going to do. We kept in contact the whole time.
"He's a valuable Test player, and his performance in the World Cup and the Six Nations indicated there's still more in him. I'm delighted by his decision."