In April, the Bayern squad took a 20-percent reduction in salary, but Hainer did not specify how large the cut was this time.
"It is very satisfying to see that our team understands the situation and will again give up part of their salary until the end of the season," Hainer told German daily Bild.
Bayern sit seven points clear of second-placed Borussia Dortmund at the top of the Bundesliga with six games remaining as they look set to win a record-extending eighth straight title.
The German top-flight season is scheduled to end on June 27, although Bayern could potentially also be in the German Cup final on July 4.
Hansi Flick's side are also still in the Champions League, after a 3-0 victory at Chelsea in their last 16 first leg before the coronavirus lockdown, but UEFA are yet to announce how it plans to end that competition.