Student Loan IDR Calculator

How Income-Driven Repayment (IDR) Works

If your federal student loan payments feel unmanageable compared to your salary, an Income-Driven Repayment (IDR) plan is the standard escape hatch. Instead of a fixed 10-year payoff schedule, IDR plans cap your monthly payment at a percentage of your discretionary income.

The Department of Education defines discretionary income as the difference between your Adjusted Gross Income (AGI) and 225% of the federal poverty guideline for your family size. Under the newest SAVE plan, you pay 10% of that discretionary income (or 5% for undergraduate loans). If your calculated payment is lower than the monthly interest, the government subsidizes the difference so your balance doesn't balloon.

Public Service Loan Forgiveness (PSLF)

PSLF is the most powerful student loan program in the country. If you work full-time for a qualifying employer — such as a government agency, a 501(c)(3) non-profit, or the Peace Corps — you can have your remaining balance forgiven completely after 120 qualifying payments (10 years).

The key advantage of PSLF is that the forgiveness is entirely tax-free. Other IDR plans (like IBR or PAYE) forgive balances after 20 or 25 years, but the IRS treats that forgiven amount as taxable income. Under PSLF, you don't owe a dime in taxes on the forgiven balance. This calculator models the PSLF timeline based on the years of public service you enter.

The Trap of Negative Amortization

If you have a $100,000 loan at 7% interest, your balance grows by about $583 a month. If your IDR payment is only $200, you are technically making your required payments, but your balance is increasing by $383 every month. This is called negative amortization.

In the past, this was a major trap. However, under the SAVE plan, the Department of Education waives the unpaid interest so your balance doesn't grow. If you are on an older plan (like IBR or PAYE) and pursuing PSLF, negative amortization is mathematically fine because the entire balance will be wiped out after 10 years. But if you are not pursuing PSLF, a growing balance is a financial emergency that requires a higher income or a switch to a different plan.

Marriage and Filing Taxes Separately

If you are married, how you file your taxes has a massive impact on your IDR payment. If you file a joint tax return, both you and your spouse's incomes are used to calculate your discretionary income. This can double your monthly payment.

If you file taxes separately, only your income is counted under the SAVE and PAYE plans. The trade-off is that filing separately usually results in a higher overall tax bill. You have to run the math both ways: compare the savings on your student loan payment against the extra tax liability.

When to Refinance Student Loans

Refinancing replaces your federal loans with a private loan at a lower interest rate. It can save you thousands of dollars if you have strong credit and a high income. However, you lose all federal protections when you refinance.

You can no longer use IDR, and you forfeit PSLF forever. If you are a doctor or lawyer working for a non-profit and pursuing PSLF, refinancing is almost always a catastrophic mistake. But if you are a high-earning software engineer in the private sector with a small balance, refinancing to a 4% private loan can be a smart financial move. The calculator above helps you see the IDR baseline before making that leap.