The SPFL have confirmed that the last-ditch attempt at league reconstruction has failed.
That means Dundee United and St Johnstone will kick off the new top-flight campaign, scheduled for August 1, in a 12-team Premiership.
Hearts will be relegated, while only the Tangerines will make the step-up as champions.
The Championship will stay at 10 clubs, as will Leagues One and Two, with Dundee, Dunfermline, Raith Rovers and Arbroath playing only 27 matches, beginning on October 17.
Hearts owner Ann Budge had proposed that her team, Partick Thistle and Stranraer would be saved from their respective drops, while Kelty Hearts and Brora Rangers would be added to the list of senior clubs.
The plan required the support of 11 of the 12 top-flight sides as well as 75% of all 42 sides, and thus fell well short with only 16 teams backing it.
SPFL chief executive Neil Doncaster, who had asked clubs to declare one way or the other by 10 am this morning, confirmed: “In recent weeks, we’ve been consulting closely with our clubs regarding possible reconstruction and, based on the feedback we received, the board decided to ask all 42 clubs to give their views so that we could have absolute clarity, which we’ve achieved today.
“Whilst a number of clubs were in favour of a new divisional set-up, the support for it was insufficient and we will now move forward with a fixture programme for season 2020/21 based on the current 12-10-10-10 structure.
“Due to the restrictions forced upon us by the coronavirus outbreak, the Championship clubs also voted overwhelmingly to play each other three times next season, rather than four, which enables a later start to the Championship league season.
“Now that we have a confirmed structure for next season, the SPFL’s fixturing team will begin work on the Premiership fixture list, which will start on the weekend of 1 August, and the Championship fixture list, which will start on the weekend of 17 October.”
The other two divisions have yet to receive start dates.
Hearts moved quickly to confirm that they would be taking court action.
In statement, they said: “Now that all other avenues are closed, we are left with no choice but to proceed with a legal challenge.
“The club has tried throughout these last few months to avoid this course of action but we must now do the right thing by our supporters, our employees, our players and our sponsors, all of whom have been unwavering in their commitment and support.
“We can hold our heads up high as we have acted at all times with integrity, common sense and with the best interests of Scottish football at heart.
“We have stated from the beginning that the unjust and unfair treatment of Hearts, Partick Thistle, Stranraer and indeed other clubs cannot be allowed to go unchallenged.
“While many weeks have been wasted in trying to find a solution, we must now formally challenge this outcome.
“The club can confirm that the necessary steps have been taken to begin this legal challenge. Given that this is now an active legal matter, the club will be offering no further comment at this time.”