The former Manchester United and Newcastle United midfielder, 35, has been served with a creditor's petition and is listed in an official receiver bankruptcy notice published today.
He played last season with Glentoran in the Irish Premiership and is one of Northern Ireland's most capped players with 86 appearances since his debut in 1994.
A Revenue and Customs spokesman confirmed it had taken action against Gillespie, who has an address in Bangor, Co Down, over a tax bill.
He refused to say how much the service was owed.
Gillespie was a member of Manchester United's 1992 FA Youth Cup winning team and represented the Red Devils until 1995 when he moved to Newcastle.