Part of the confusion lies in rules changing throughout time. This post will talk about deferment only, and not forbearance.
The initial medical internship/residency deferment applies to FFEL loans made before July 1, 1993. That deferment option ended (was no longer re-authorized by Congress) but those loans originated before July 1, 1993 were grandfathered in. Most likely this does not apply to any medical student, resident, or fellows.
Since then, residents/fellows were able to take advantage of the 20/220 economic hardship deferment. Economic Hardship Deferment allows the borrower to avoid making payments for up to three years, during which time the federal government will pay the interest on the subsidized portion of federal loans. This option wasn't restricted to just medical residents/fellows but anyone who met the criteria. To qualify for Economic Hardship Deferment, your monthly debt payment must exceed 20% of your income, and your income cannot exceed 220% of the Federal Poverty Level. The 20/220 economic hardship deferment had a 3 year limit.
The College Cost Reduction and Access Act of 2007 (CCRAA) removed the 20/220 economic hardship deferment option. The language of the law states that it was effective October 1, 2007. Fortunately the US Dept of Education allowed the 20/220 economic hardship deferment to remain in place while it issued its final regulations for CCRAA. 20/220 economic hardship deferment ended July 1, 2009.
The new income-based repayment plan (IBR) became effective on July 1, 2009. It sets your monthly payments at 15% of your income that exceeds 150% of the poverty line. The government pays the unpaid interest for up to three years when the monthly payment under IBR is less than the interest that accrues. After that point any unpaid interest is deferred and will be capitalized when the borrower no longer qualifies for IBR.
Perkins loans are not eligible for IRB unless it is part of a consolidated federal loan.
The 20/220 rule and IRB applies to any federal loans made after July 1, 1993.
For any federal loans made after 1993, you still have the option for deferment but only under limited conditions.
1. Student - at least half-time in a post-secondary education program
2. Study in an approved graduate fellowship program or in an approved rehabilitation training program for the disabled
https://www.dl.ed.gov/borrower/Defe...ardName=Graduate Fellowship Program Deferment
3. Unable to find full-time employment (limited to 3 years)
4. Economic hardship (includes Peace Corps Service) if your income is less than 150% of poverty guidelines ($1353/month for a one person) or you are on the state public assistance program.
5. Active Military Duty (and if after Oct 1, 2007, for additional 180 days after demobilization)
Please note that the economic hardship deferment under this current system is different than the 20/220 economic hardship deferment that was elimited on July 1, 2009.