I am trying to calculate how much I will have to pay under a 10 year repayment plan if I lose IBR eligibility once I begin filing joint tax returns with my wife.  I have been making IBR based payments for the last 3 years and will be applying for public service loan forgiveness in 7 years.  I would like to calculate the monthly payments that I would be making once my payments convert into the 10 year standard repayment plan.  This will determine whether I will file jointly with my wife or married but separate. My question is, what is the amount that the 10 year standard repayment based off of?  Is it based on the principal amount i originally took out on my loans (i.e. the amount quoted on the promissory note)? Is it based off of the amount that I owe once my repayment converts to 10 year standard repayment? (which is higher than the principal note balance given that interest has accrued at a larger rate than the payments that Ive been making on a monthly basis?  Put simply, I took out $260k in loans for medical school, which now have a balance of $293k.  What amount (im assuming its one of these 2) will my loan servicer use to calculate what my monthly payments should be under a 10 year standard repayment plan?

If you qualify for forgiveness don’t file jointly. Unless the tax you pay is more than the money you would save on payments keep filing separately. The link is below. Allows you to login and check at different income and tax types to see a estimated payment. My wife and I are doing this and her loans are at $0 a month which saves us 6K a year but cost us $1,400 on taxes.

https://studentloans.gov/myDirectLoan/mobile/repayment/repaymentEstimator.action

Also to answer your original question it’ll be based off your current balance (293k for you) and the amount of years you have left.  So in essence how much will it take based on even payments to pay off 293k in 84 months (7 years x 12 months)...cmilliorn has the right formula for figuring out your break even.  Talk to a tax guy if you aren’t sure!