MC HAMMER OWES OVER $700,00 IN TAXES

The U.S. government isn't letting MC Hammer off the hook for the $779,585 it claims the rapper owes in back taxes -- and has now filed a lawsuit against the rapper and his wife ... to recoup its losses.

According to the docs, obtained by TMZ, the back taxes are from Hammer's most financially troubled years -- 1996 and 1997 -- and Uncle Sam wants the money back stat,