When a federal court vacated SAVE in March 2026 and the One Big Beautiful Bill Act finished it off by statute, two income-driven repayment plans were left standing: RAP, available from 1 July 2026, and IBR. Coverage since has mostly described the formulas. Almost none of it says which one actually costs less, for whom, and by how much.
So we computed it. Both plans, every income from $0 to $300,000 in $100 steps, crossed with family sizes 1 to 6 and dependent counts 0 to 4 — 20 household configurations in all.
The finding: RAP is cheaper in only 3 of 20 household configurations, and never by more than $50.50 a month. Where IBR is cheaper — which is nearly everywhere — it can be cheaper by $554.50 a month. The downside of ending up on the wrong plan is about ten times the upside. And because IBR is closed to loans issued on or after 1 July 2026, new borrowers are placed on the losing side of that trade by default.
The two formulas, and why they diverge
RAP charges a percentage of your total adjusted gross income, stepping up one point per $10,000 of income to a 10% cap, then subtracts $50 per dependent and floors the result at $10. IBR charges a percentage of discretionary income only — the portion of AGI above 150% of the federal poverty guideline for your family size.
That structural difference produces the whole result. Here is a single borrower with no dependents:
RAP steps up in $10,000 income brackets, which is why its line is a staircase. IBR sits at $0 until income clears $23,940 — 150% of the 2026 poverty guideline for a household of one — then rises in a straight line.
Below $23,940 an IBR payment is genuinely zero, while RAP's floor means you still owe $10. RAP then wins a middle stretch. Above about $80,000 IBR pulls ahead and never gives the lead back.
$71 versus $50
One comparison explains the entire result.
Each additional person in your household raises IBR's exempt income by $8,520 — 150% of the $5,680 poverty-guideline step — which reduces an IBR payment by $71 a month. Each dependent reduces a RAP payment by $50 a month.
So every extra person in the household pushes the two plans $21 a month further apart, in IBR's favour. RAP does give a household allowance; it is simply smaller than the one it is competing against. This is why RAP loses ground as families grow rather than gaining it, and it is the opposite of what the $50-per-dependent headline suggests.
Where RAP actually wins
Only three configurations out of twenty, all of them narrow:
| Household | RAP cheaper between | Best-case saving |
|---|---|---|
| 1 person, 0 dependents | $30,000 – $80,000 | $50.50/mo at $50,000 |
| 2 people, 1 dependent | $37,900 – $70,000 | $29.50/mo at $50,000 |
| 3 people, 2 dependents | $48,400 – $60,000 | $8.50/mo at $50,000 |
| All 17 other configurations | Never | — |
Note what is missing. Any household of two or more claiming no dependents: IBR cheaper at every income. Any household of four or more, whatever the dependent count: IBR cheaper at every income. The three RAP wins are all small, all clustered near $50,000, and the third is worth $8.50 a month.
The penalty is fixed above $100,000
Above $100,000 RAP is capped at 10% of total AGI, and IBR charges 10% of income above the threshold. Both are then 10% lines with the same slope, so the gap between them stops growing and becomes constant — exactly 10% of the exempt income, divided by 12, less $50 per dependent.
| Household size | 150% of poverty guideline | RAP costs more by (0 dep) | Per year |
|---|---|---|---|
| 1 | $23,940 | $199.50/mo | $2,394 |
| 2 | $32,460 | $270.50/mo | $3,246 |
| 3 | $40,980 | $341.50/mo | $4,098 |
| 4 | $49,500 | $412.50/mo | $4,950 |
| 5 | $58,020 | $483.50/mo | $5,802 |
| 6 | $66,540 | $554.50/mo | $6,654 |
A borrower on $110,000 and a borrower on $250,000 with the same family size pay the same penalty for being on RAP. It does not taper.
Why this matters more than a plan comparison usually would
Ordinarily an unfavourable plan is an avoidable problem — you compare and pick the other one. That option is closing. IBR is not available for Direct Loans issued or consolidated on or after 1 July 2026, which makes RAP the only income-driven plan for new borrowers.
So the population most affected by this arithmetic is precisely the population with no ability to act on it. A borrower who takes out loans today, marries, and has two children will spend their repayment years on the plan that costs several hundred dollars a month more than the one their older colleague is on.
Two things do sit on RAP's side of the ledger, and they are not nothing. Unpaid interest is waived rather than capitalised, so a low payment never inflates the balance — a genuine flaw in IBR, where a borrower can owe more after years of payments than they borrowed. And the government tops up any shortfall so principal falls by at least $50 a month. Against that, RAP's forgiveness clock runs 30 years against IBR's 20 or 25.
Whether those protections are worth several thousand dollars a year is a judgement call. Knowing the size of the trade is not — and that number has not been published anywhere we could find.
Method
Both plans were evaluated with the formulas as legislated, using the 2026 HHS poverty guidelines for the 48 contiguous states and DC ($15,960 for a household of one, rising $5,680 per additional person). Alaska and Hawaii use higher figures and would shift every threshold up.
- RAP: max($10, AGI × bracket rate ÷ 12 − $50 × dependents), where the bracket rate is 1% for AGI of $10,001–$20,000 and rises one point per $10,000 to a 10% cap above $100,000.
- IBR: max($0, AGI − 1.5 × poverty guideline) × 10% ÷ 12, using the post-July-2014 borrower rate.
- Sweep: AGI $0–$300,000 in $100 increments, family sizes 1–6, dependents 0–4.
Every figure here is reproducible in the Income-Driven Repayment Calculator — enter the same income, family size and dependent count and you will get the same two numbers. Spousal income and filing status are excluded, as is the older 15% IBR tier for pre-July-2014 borrowers, which shifts the single-filer crossover down to about $27,700.
Figures are estimates for comparison, not advice. Confirm your own options at studentaid.gov or with your servicer before switching plans.