London football club Leyton Orient has been served with a winding-up petition by HM Revenue and Customs.
The petition was delivered to the club on 2 February, with a hearing to be held at the High Court on 20 March.
The struggling League Two club are currently second bottom in the table, and in danger of going out the Football League.
A 4-1 defeat at Stevenage on Tuesday evening left them six points adrift of safety.
Orient president Francesco Becchetti said last month that he would consider selling the club, which he took over in 2014.
However, it is understood a number of potential offers have not been considered sufficiently financially attractive.
While the taxman is the principal petitioner for a winding-up, it now remains to be seen whether other creditors will come on board and support the action.
In the most recently available financial results, for the year ending 30 June 2015, Leyton Orient put their book value, the net value of the company running the football club, at -£5,512,449 - in other words, the club had debts exceeding its assets of more than £5.5m.
A spokesman for the EFL said it was aware of the winding-up petition, and had been in contact with the club asking them for further information and observations about the situation.
'In a hole'
A meeting of the Leyton Orient Fans Trust (Loft) supporters' group will take place on Thursday to establish a financial "fighting fund" to help revive the club should it go into liquidation.
"This is a cause for alarm, but given the way things have been going recently we suspected something like this was coming down the track," said Tom Davies, vice-chairman of Loft.
"Obviously it is concerning to get a winding-up petition, and we are worried about how the owner will react, if indeed he does react to this."
Davies said the HMRC action would give extra focus to the fan meeting, and called on supporters to rally around to save the club.
"We need new funding, and a new owner," he added. "Other clubs have survived periods like this and gone on to flourish, but first of all we need to get out of the hole we are in at present."