James Holmes -- Facing EVICTION Prior to 'Batman' Massacre

James Holmes was just days from possibly being kicked out of his Colorado apartment when he opened fire in a crowded movie theater and killed 12 people ... this according to his neighbors.

Two residents of Holmes' apartment building tell TMZ ... in order to live in the complex you MUST be enrolled in the university. As soon as your student status is axed, you only have 30 days to move out.

We're told the building takes this rule very seriously and checks residents' active status every single month like clockwork. Holmes was a University of Colorado student at one time, but school officials say he dropped out some time in June.

That means Holmes was just about at the end of his 30-day grace period to move out of his apartment when he took an arsenal of weapons to a local theater and opened fire.