'Kill Bill' Star Michael Madsen -- Goes Deadly Viper Squad on Tax Liens

"Kill Bill" star Michael Madsen took a katana sword to $640,000 worth of lingering IRS bills -- and paid 'em off, TMZ has learned.

Two separate liens were filed against Madsen way back in 2008 ... for unpaid taxes in 2004 ($317,443.95) and unpaid taxes in 2006 ($327,099.47). Total damage: $644,543.42.

According to docs filed on August 8th both liens were paid off.

Good thing, otherwise Uncle Sam may have gone to plan B: the black mamba.