Boston United officials "propped up" their ailing club by failing to properly report earnings to the taxman, a court has heard.
They disguised wages and bonuses as expenses, Southwark Crown Court heard.
The scheme was so successful it transformed the Lincolnshire club's fortunes, prosecutor Martin Hicks said.
Club general manager John Blackwell, 59, and ex-club accountants Brian James and Ian Lee, 57, deny conspiring to cheat the public revenue.
The public revenue was left more than £323,000 the poorer as a result of the four-year plot, the court was told.
The club went from employing part-time players to full-time ones, and saw its gates swell by a massive 1,000%, Mr Hicks said.
"In doing so Boston United undoubtedly secured a competitive advantage, an advantage over rival football clubs, their players and their supporters at a time when promotion to the higher leagues was seen as key to the club's survival."
The three men are charged with cheating the public revenue between 5 April 1997 and 1 June 2002.
Club manager Steve Evans, 43, and one-time chairman, Patrick Malkinson, 64, of Boston, have pleaded guilty to the same charge.
Mr Hicks said: "The method deployed was simple - wages to various players and staff which attract tax were disguised as out-of-pocket expenses which do not attract tax.
"Various fees and bonuses, such as signing on fees or winning bonuses, went undisclosed when they should have been declared."
He added: "The motive for the cheating was not one of personal greed. At the time the club was going through financial difficulties and was at risk of going under."
Mr Hicks told the court that the club moved from a struggling club in the Unibond League in 1997 with gates of some 400 to League Two in 2001 with gates of 4,000.
The trial continues.