Sheffield Wednesday will "imminently" be served with a winding-up petition over money owed to HMRC, reports BBC Radio Sheffield.
After an investigation alongside the Sheffield Star it is understood the Championship club owes £1m.
A winding-up petition would increase the pressure on the club's owner Dejphon Chansiri to sell.
They are already under six separate EFL embargoes after failing to pay wages on time in five of the past seven months.
Wednesday are second bottom of the Championship with six points from nine games after a torrid period off the field has left them with a threadbare squad.
The severity of the situation became apparent when May's wages were not paid on time, in the wake of the same thing happening in March.
With uncertainty ongoing and the club placed under various registration embargoes, highly-rated manager Danny Rohl departed in July and his assistant Henrik Pedersen took charge 10 days before the season started.
The team did not play a single pre-season friendly in front of fans and players pulled out of a training match against Burnley after July's wages were not paid.
Fans have organised protests before and during games so far this season and they boycotted the home EFL Cup ties with Leeds and Grimsby, while the supporters' trust also encouraged fans not to buy drinks or snacks in the stadium.
Thai businessman Chansiri, who has owned the club for the past 10 years, has been absent for the entire period and, as yet, no sale has been close.