One more thing about  documentation for eligibility. What happens if I fail to re-certify for my income-driven repayment plan in a timely manner.
You would be removed for the income-driven repayment plan and your monthly normal amount would probably increase  if you miss the recertification time.
What would be the different payment periods?
Under all four plans, any remaining loan balance is forgiven if your federal student loans are not paid in full at the end of the repayment period.