IDR payment estimator — SAVE, IBR, PAYE, ICR

What the calculator computes and why the plans diverge

The federal student loan system offers four income-driven repayment plans, each built on the same structural idea — tie the monthly payment to what the borrower earns rather than what the borrower owes — but each plan implements that idea with different parameters. The two variables that produce the divergence are the percentage of discretionary income the plan claims and the definition of "discretionary" itself, which hinges on how large a multiple of the federal poverty guideline is subtracted from adjusted gross income before the percentage is applied.

SAVE, the newest plan (formerly called REPAYE and restructured under the Biden administration's 2023 rulemaking), is the most generous on both fronts for undergraduate borrowers: it uses only 5% of discretionary income and defines the poverty-level exclusion at 225% of the federal poverty guideline. For a single borrower earning $50,000, SAVE shelters the first $35,910 of income from the payment calculation, then takes 5% of the remaining $14,090, producing a monthly payment of roughly $59. The same borrower under IBR (post-2014 version) shelters only $23,940 (150% of the poverty guideline) and pays 10% of the remainder, producing roughly $217 per month — more than three times higher. Under old-IBR, the rate climbs to 15%, and the payment reaches roughly $326. Under ICR, the shelter drops to 100% of the poverty level and the rate rises to 20%, yielding roughly $567 per month. These are not rounding differences; the plan choice can determine whether a borrower's monthly student loan obligation is manageable alongside rent and groceries or whether it crowds out the rest of the budget.

The poverty guideline and family size

The federal poverty level published annually by the Department of Health and Human Services is the baseline that all IDR formulas reference. For the 2026 guideline year (which applies to the contiguous 48 states and the District of Columbia), the poverty level for a household of one is $15,960. Each additional family member adds $5,680, so a family of four has a poverty guideline of $33,000. Alaska and Hawaii have higher guideline figures and are not modeled in this calculator.

Family size in the IDR context includes the borrower, a spouse (unless filing separately under plans that honor Married Filing Separately), and any dependents claimed on the borrower's federal income tax return. Adding a dependent — a child, for instance — increases the poverty-level exclusion and reduces the monthly payment across every plan. For a borrower earning $50,000, moving from a family size of one to a family size of three shifts the SAVE payment from $59 per month down to $0, because the 225% exclusion for a family of three ($61,470) exceeds the borrower's entire $50,000 income. This is one of the most financially consequential — and least discussed — interactions in the student loan system: family composition directly reduces the monthly obligation through the poverty guideline arithmetic.

Where the loan balance actually matters

The monthly IDR payment is not a function of how much you owe. It is a function of how much you earn. A borrower with $25,000 in federal loans and a borrower with $200,000 in federal loans will make the same monthly IDR payment if their AGI and family size are identical. This design is deliberate — income-driven repayment is an affordability mechanism, not an amortization schedule — but it produces a structural tension. When monthly payments are low relative to accruing interest, the loan balance grows each year (negative amortization). After 20 or 25 years of payments, the remaining balance is forgiven. The American Rescue Plan Act exclusion that made IDR forgiveness tax-free expired on December 31, 2025, so beginning in 2026 that forgiven balance is once again taxable ordinary income in the year of discharge — the so-called "tax bomb" (PSLF forgiveness stays tax-free). See our student loan tax bomb analysis.

For borrowers pursuing Public Service Loan Forgiveness (PSLF), the calculus is different: PSLF discharges the remaining balance after 120 qualifying payments (10 years of full-time public service employment), and PSLF forgiveness is tax-free by statute. The interaction between IDR plan choice and PSLF is covered in detail in the IDR plans deep dive, but the short version is that PSLF borrowers should generally choose the plan that minimizes monthly payments, because every dollar paid before forgiveness is a dollar that would have been discharged tax-free. For non-PSLF borrowers, the analysis is more complex: lower payments mean more negative amortization, a larger forgiven balance, and a potentially larger tax bill at the end of the repayment term.

What replaced SAVE — RAP and the IBR fallback

SAVE was challenged in federal court almost immediately after its final rule took effect, and was ultimately struck down. Its hallmark interest-free forbearance ended and interest resumed on SAVE loans on August 1, 2025. Under the 2025 reconciliation law the plan is replaced by the Repayment Assistance Plan (RAP), available July 1, 2026, with IBR the surviving traditional plan. Borrowers on the phased-out plans have until July 1, 2028 to switch to RAP or IBR. Verify your options at studentaid.gov before recertifying.

If SAVE is unavailable, IBR is the default statutory fallback for most borrowers with Direct Loans. PAYE is available only to a narrower population (no outstanding loan balance before October 2007, with a disbursement on or after October 2011). ICR is available to all Direct Loan borrowers and is the only IDR plan that accepts parent PLUS loans after consolidation into a Direct Consolidation Loan — but its terms are the least favorable, with a 20% rate against only 100% of the poverty guideline. The comparison table in the widget above lets you see the payment under every plan simultaneously, so the fallback decision has numbers behind it rather than guesswork.

When refinancing into a private loan makes sense — and when it does not

A borrower on IDR who sees a private lender offering a 5.0% fixed rate against their 6.8% federal rate faces a real temptation: the rate spread is visible, the savings are computable, and the application takes ten minutes. What the rate-spread calculation does not price is the permanent loss of IDR eligibility, PSLF eligibility, deferment during hardship, and discharge protections (death, disability, school closure) that attach to federal loans by statute and that a private refinance extinguishes the moment the federal balance is paid off. The full framework for evaluating whether a refinance is net-positive or net-negative for a specific borrower is documented in the federal vs private student loan refinance comparison. The short heuristic: if you are pursuing PSLF, are on a low-payment IDR plan, or have any realistic expectation of needing hardship forbearance in the future, refinancing into a private loan is almost certainly a net loss disguised as a rate improvement.

What this calculator deliberately leaves out

Several things, all material. It does not model the standard 10-year payment cap — under PAYE and IBR, your IDR payment is capped at the amount you would pay under the standard 10-year repayment plan, so borrowers with high incomes relative to their balance may hit the cap and pay less than the raw formula suggests. It does not model the interest subsidy under SAVE, which covers all unpaid interest on subsidized loans and half on unsubsidized loans during periods of $0 or reduced payments. It does not model tax filing status interactions — Married Filing Separately on PAYE and IBR uses only the borrower's individual income, while Married Filing Jointly uses combined household AGI, and the optimal filing choice requires modeling the tax cost of MFS against the IDR payment savings. And it does not project total cost over the repayment term, which requires assumptions about income growth, family size changes, and forgiveness timing that would make the output speculative rather than mechanical. The widget gives you the monthly payment under today's inputs; the long-term projection requires a different kind of analysis.