Can I change jobs after I-140 is approved?

Yes, but with conditions:

• Before I-485 filed: Must restart Green Card process with new employer
• After I-485 pending 180+ days: Can use AC21 portability to change employers
• New job must be in same or similar occupation
• Priority date may be preserved

AC21 allows: Job change if I-140 approved and I-485 pending 180+ days, and new job is same/similar occupation.