- 6 months from when you stopped school (grace period doesn’t count)
- any time you were in default or bankruptcy
- any time you returned to school.
So, if you completed undergrad in ‘96, but then returned to school in ’07 until ’10, assuming no default or bankruptcy, you would have roughly 23 years of credit.
Undergrad loans are forgiven once 20 years of credit, grad loans are forgiven at 25 years. So you’d want to finish up the remaining two years on an IDR for any grad loans – likely SAVE, but it can vary.