Tebas is part of a working group set up by UEFA to devise solutions for the "resumption and/or conclusion of the current season in a coherent manner".
LaLiga's chief is confident things can be wrapped up by the end of June, though he acknowledged around six weeks of competition would be required.
"The fundamental scenario is that mid or late May is the latest starting date to end on June 30," said Tebas in an interview with El Pais.
"The scenario may also depend on some Champions League games that will be played at the weekend, which could give us some room to start some clubs later, or that we can recover by starting all a little later.
"We are even working with leagues like the Italian one, which has 14 games left, and the Danish one, which has 15 remaining. The decision of UEFA to postpone the European Championship has served us well to try to finish the competitions.
"We made the calendar calculations even before the European Championship was postponed. It was a stage that we knew could be reached and we are working on various start dates.
"Here you have to work backwards, with what is the last date on which you could play to see the options that may arise.
"When we start playing there will be full medical guarantees, but that no longer depends on us, it will depend on the governments of the countries. If they guarantee that it can be played, it will be played."
Tebas insisted there are no plans to cut down on fixtures and admitted fans could be kept out of games when they resume.
He said: "That will also depend on the governments of each country. You have to think that we are working with 30 different leagues and it will depend on the health authorities if it is played behind closed doors or under what conditions.
"We are not considering any format change for any competition, including the European ones. The mandate that we have is to finish the competitions as they are now. The calendar with which it works is with the competitions in full and in their usual format.
"The only job that concerns me day and night is to finish the competitions."