Bolton Wanderers have received a winding-up petition from HMRC over unpaid PAYE and VAT tax bills.
The Championship club is believed to be losing £1m per month and has outstanding bills owed to HMRC worth around £600,000.
Its playing squad, currently positioned bottom of the Championship, went unpaid in November as owner Eddie Davies and club advisor Trevor Birch look to find a buyer.
Bolton, who have £172.9m in debt, had asked for additional time to arrange a sale or find additional funds but HMRC decided to serve the petition which increases the threat of administration.
Trevor Birch, who is acting as financial advisor, said:
Quite clearly the club remains in a critical financial position. We will continue to try and finalise a sale or alternatively raise some short term funds needed to give the club a breathing space and time in which to consider its options.
Four parties are reported to be interested in a potential purchase of the club, yet if a deal cannot be reached Birch may have to file for registration which carries with it an immediate 12 point deduction in the Football League.