RAP vs IBR: Which Income-Driven Plan Is Actually Cheaper?

With SAVE gone, most student loan borrowers are choosing between two income-driven plans: the brand-new RAP and the surviving IBR. Neither wins every time — the answer depends on your income, family size, and balance. Here's how both formulas work, and the math for three different student loan borrowers.

Published October 10, 2026 · 12 min read

The two plans side by side

Before the math, the architecture. These are the features that decide which plan fits whom:

The two structural details that matter most are the cap and the interest waiver. RAP's interest waiver is generous to student loan borrowers whose payments can't cover monthly interest — your balance stops growing no matter how small the payment. IBR's payment cap is generous to student loan borrowers whose income is high — your payment can never exceed what Standard would have charged. Each plan protects a different kind of student loan borrower.

How RAP payments work

RAP sets your payment as a slice of your adjusted gross income, and the slice gets bigger as income rises. Roughly: 1% of the income in the $10,000–$20,000 band, then an extra percentage point for each $10,000 band above that, reaching 10% on income above $100,000. The bands are marginal — you only pay the higher rate on the dollars inside that band, not on your whole income. Income of $10,000 or less means a flat $10 a month. Then $50 a month is subtracted for each dependent, with a $10 monthly minimum.

Example to make it concrete: a single student loan borrower with a $55,000 AGI. The math runs $100 for the $10k–$20k band (1%), $200 for the next (2%), $300 (3%), $400 (4%), and $250 for the final $5,000 (5%) — $1,250 a year, or about $104 a month. No dependents, no further subtraction. That payment is the same whether the student loan borrower owes $20,000 or $200,000, because RAP bills off income, not balance.

The other half of RAP is the part people miss: if your payment doesn't cover that month's interest, the unpaid interest is waived. On a $90,000 balance at 6%, monthly interest is about $450. A $104 payment would leave $346 of interest unpaid every month on a normal plan — the balance would climb. Under RAP, that $346 is wiped out, and the government matches up to $50 of your payment toward principal. The catch to verify in current guidance: these protections apply in months you pay as scheduled. Miss payments and the protection can pause.

How IBR payments work

IBR bills off discretionary income, not total income. Discretionary income means your AGI minus 150% of the federal poverty guideline for your household size (for a single person in 2026, that threshold is $23,940 — verify the current table at studentaid.gov, since it updates yearly). Newer student loan borrowers — those whose first federal loan was on or after July 1, 2014 — pay 10% of that discretionary amount, divided by 12, with forgiveness after 20 years. Older student loan borrowers pay 15% with a 25-year horizon.

Same $55,000 single student loan borrower: discretionary income is $55,000 minus $23,940, or $31,060. Ten percent of that is $3,106 a year — about $259 a month. That's roughly two and a half times the RAP payment for the same person.

But IBR has the ceiling RAP doesn't. Your IBR payment can never exceed what the 10-year Standard plan would have charged on your loans. On a $28,000 balance at 6%, the 10-year Standard payment is about $311 a month. If the IBR formula says $592, you pay $311 — the cap binds, and Standard-equivalent payments still count toward forgiveness. For high earners with modest balances, that cap is the whole reason IBR exists.

One more difference with real consequences: IBR payments can be $0 if your income is low enough, while RAP has a $10 floor. And on IBR, unpaid interest accrues — there's no equivalent of RAP's monthly waiver. A $0 or tiny payment on a large balance means the balance grows, month after month. Compare the two plans' official formulas at studentaid.gov's repayment plan page before you decide.

Video: "The $10 Student Loan Payment That Still Shrinks Your Balance — RAP vs IBR, With Numbers" — worked payment math for both plans across several student loan borrower scenarios.

Three worked student loan borrower profiles

Formulas are abstract. Here are three student loan borrowers — each labeled clearly as an illustrative example, simplified, not a quote. Assume 6% interest, 2026 poverty guidelines, and newer-student loan borrower IBR terms (10% / 20 years). Your real numbers will differ; run them through the Loan Simulator at studentaid.gov.

Profile A: Single, $55,000 income, $35,000 balance

• RAP: ~$104/month (the bracket math from the section above; no dependents).
• IBR: ~$259/month (10% of $31,060 discretionary income).
• Standard (10-year): ~$389/month.

Winner: RAP, by a mile. The monthly payment is 60% lower than IBR's, and because RAP waives unpaid interest (monthly interest here is about $175), the balance holds steady instead of growing — while $50 a month still chips at principal. IBR costs more per month and takes roughly two decades to clear. Standard is nearly four times the RAP payment. If this student loan borrower is watching the SAVE transition deadlines, RAP is the plan to lock in before the window closes.

Profile B: Married, $70,000 household income, family of 4, $90,000 balance, nonprofit worker chasing PSLF

• RAP: Bracket math on $70,000 gives ~$175/month, minus $50 per dependent for two kids = ~$75/month.
• IBR: Discretionary income is roughly $70,000 minus ~$48,000 (150% of the poverty guideline for a family of four) = ~$22,000. Ten percent = ~$181/month.
• Standard (10-year): ~$999/month.

Winner for cash flow: RAP. And for PSLF seekers, plan choice matters more than the monthly number — because what actually counts is 120 qualifying monthly payments while working for a qualifying employer, after which the remaining balance is forgiven tax-free. Both RAP and IBR count. With RAP at $75/month, ten years of PSLF-track payments total about $9,000 before the remaining balance is wiped out tax-free. That's the best deal in the entire federal loan system for this student loan borrower — but only if the plan stays qualifying and the employer certification stays current. One caution: RAP has no payment cap, so if household income rises sharply over the decade, the payment follows it up. Re-run the comparison at each annual recertification.

Profile C: Single, $95,000 income, $28,000 balance

• RAP: Bracket math runs $100 + $200 + $300 + $400 + $500 + $600 + $700 + $800 + $450 (9% on the $5,000 above $90k) = $4,050/year = ~$338/month.
• IBR: Formula says ~$592/month — but the cap binds at the 10-year Standard amount = ~$311/month.
• Standard (10-year): ~$311/month.

Winner: Standard. When IBR's uncapped formula exceeds the Standard payment, the cap turns IBR into Standard-with-extra-steps — so skip the complexity and take Standard directly. This is the crossover the table warned about: above roughly $80k–$100k of income for a single student loan borrower, the formulas flip and income-driven plans stop helping. Standard pays the balance off in a decade, accrues the least total interest, and — critically — leaves no forgiven balance to be taxed later.

The forgiveness-tax wrinkle

Here's the detail that changes the total-cost picture: the federal tax exclusion for forgiven student loan balances — in place from 2021 through 2025 — has expired. Forgiven balances under RAP or IBR may be federally taxable starting in 2026. That means "forgiven after 30 years" isn't the end of the story; it's the end of the story minus a tax bill.

The rough math: if $40,000 is forgiven and you're in the 22% marginal bracket, that's roughly an $8,800 tax bill arriving in a single year. At a 12% bracket, about $4,800. Neither is a reason to skip an income-driven plan you need — but both are reasons the total cost of RAP's 30-year path can be higher than the monthly payment suggests. Our deep dive on the tax bill on forgiven balances walks through how to estimate yours and how student loan borrowers plan for it.

And the exception that matters: PSLF forgiveness remains federally tax-free — see the official requirements at studentaid.gov's PSLF page. That's another reason Profile B's nonprofit worker should treat PSLF as the prize — the 10-year path dodges both the extra decade of payments and the tax bill.

Bottom-line decision rules

You now have everything the profiles showed. If you want rules of thumb instead of a spreadsheet:

• RAP likely wins when: your income is modest relative to your balance; you have dependents (the $50/month-per-dependent subtraction is genuinely valuable); you want the lowest possible monthly payment; or you're worried about your balance growing — RAP's interest waiver is the only plan feature that stops that.
• IBR likely wins when: your income is higher (roughly $80k+ single); your balance is modest enough that the Standard cap binds; you're already years into IBR and close to the 20- or 25-year forgiveness line (switching to RAP's 30-year horizon would reset the math); or you want payment certainty with a hard ceiling.
• Standard likely wins when: your income-driven payment would equal or exceed the Standard payment anyway (Profile C territory); you want out of debt in 10 years; or you want to avoid any risk of a taxable forgiven balance.
• Re-run this every year. Income changes, dependents age out of the RAP subtraction, balances shrink. The RAP/IBR crossover moves with all of them. Annual recertification is required anyway — treat it as a decision point, not paperwork.

Where Department of Education guidance is still evolving — eligibility edge cases, how qualifying months transfer between plans, exact dependent definitions — verify current rules at studentaid.gov and with your servicer. Never present an uncertain detail as settled, and don't let a servicer present one either.