SAVE vs IBR: How Interest Really Adds Up

$14,200 vs $2,800: What a Payment Planner Revealed About SAVE and IBR

Two numbers. Same borrower. Same $58,000 in federal student loans. The only difference was which repayment plan she picked — and a student loan payment planner that did the math before she committed.

My friend Marisol is a school counselor in Texas. She finished her master's in 2019, consolidated her loans, and spent three years on REPAYE without really understanding what she was paying — or what she was accruing in interest. When the SAVE plan replaced REPAYE, she heard it was "better." But she also kept seeing posts about IBR. So she asked me to help her run the numbers.

Here's what we found, and how a payment planner made the difference between guessing and knowing.

Why We Needed a Planner Instead of a Calculator

Marisol had tried the Department of Education's Loan Simulator. It gave her a monthly payment estimate. That was fine. But it didn't show her the interest accrual over time — not in a way she could actually feel.

A student loan payment planner — the kind that lays out month-by-month projections, tracks unpaid interest, and shows total cost over the full repayment term — gave us something different. It showed the story.

Here's what we entered:

• Starting balance: $58,400
• Interest rate: 6.8% (weighted average)
• Income: $52,000 (AGI)
• Family size: 2
• State: Texas

Then we ran two scenarios side by side: SAVE and IBR.

SAVE Plan: What the Planner Showed

The Monthly Payment

Under SAVE, Marisol's payment was calculated at 10% of her discretionary income — defined as AGI minus 225% of the federal poverty guideline for her family size. For a family of two in the contiguous U.S., that protection was about $40,780.

So her discretionary income was roughly $11,220. Ten percent of that: about $93.50 per month.

The planner showed that clearly. But the real insight came next.

The Interest Subsidy

This is where the planner earned its keep. Each month, Marisol's $93.50 payment didn't cover the full interest accrual of about $331. Under SAVE, the government waives the remaining unpaid interest — so her balance didn't grow.

The planner projected this out over 20 years (SAVE's forgiveness timeline for graduate loans). It showed:

• Total payments over 20 years: ~$22,440
• Interest waived by the government: ~$57,000+
• Amount forgiven at year 20: ~$58,400 (the original principal, since balance never grew)

Marisol stared at that. "So I'm never actually paying off the principal?"

Basically, no. Her payments were low enough — and the interest subsidy strong enough — that the balance stayed flat until forgiveness.

IBR Plan: What the Planner Showed

The Monthly Payment

Under IBR (the newer version, for new borrowers after July 1, 2014), the payment was 10% of discretionary income — but defined as AGI minus 150% of the poverty guideline, not 225%.

For Marisol, that protection was about $27,180. Her discretionary income under IBR: about $24,820. Ten percent of that: roughly $206.83 per month.

Already, the payment was more than double the SAVE amount.

The Interest Accrual

Here is where IBR and SAVE diverge in a way that really matters. Marisol's payment under IBR was about $206.83, but her monthly interest accrual was still around $331. That means each month, roughly $124 in interest went unpaid and was added to her balance through capitalization — unless she chose to pay it out of pocket.

The planner tracked this month by month. It showed her balance creeping upward during the first several years, especially because her income grew slowly and her payment didn't keep pace with the compounding interest. By year five, her projected balance had grown from $58,400 to roughly $66,100. By year ten, it was approaching $74,000.

Under IBR, there is no interest subsidy like the one SAVE provides. Whatever your payment doesn't cover gets capitalized. That balance growth isn't just a number on a screen — it's money she would owe taxes on later if any portion was forgiven, and it's a heavier psychological weight every time she checked her loan servicer account.

The planner projected the full 20-year IBR timeline (for new borrowers). It showed:

• Total payments over 20 years: ~$49,640
• Balance growth due to unpaid interest: ~$15,600
• Amount forgiven at year 20: ~$74,000 (inflated principal plus capitalized interest)

Marisol looked at those numbers and said what most people would say: "Wait — I'm paying more each month AND I owe more at the end?"

That was exactly the point.

Side-by-Side: What the Planner Made Obvious

Once both scenarios were laid out in the same spreadsheet, the comparison stopped being abstract. Here is what the planner showed at a glance:

• Monthly payment: SAVE ~$93.50 vs IBR ~$206.83
• Discretionary income protection: SAVE shields 225% of poverty guideline vs IBR shields 150%
• Interest subsidy: SAVE waives unpaid interest monthly vs IBR capitalizes it
• Balance trajectory: SAVE stays flat vs IBR grows over time
• Total paid over 20 years: SAVE ~$22,440 vs IBR ~$49,640
• Amount forgiven at year 20: SAVE ~$58,400 vs IBR ~$74,000

The planner didn't just show payments. It showed cost. And cost is what most borrowers actually care about once they stop and think about it.

The Tax Bomb Nobody Mentions Enough

One thing the payment planner flagged that Marisol hadn't considered: forgiven loan amounts under both SAVE and IBR may be treated as taxable income at the federal level (depending on legislation and timing), and some states tax forgiven debt as well.

This matters more under IBR than under SAVE — not because the tax treatment is different, but because the forgiven amount is larger. If Marisol has $74,000 forgiven under IBR versus $58,400 under SAVE, she could face a larger tax bill years down the road. The planner estimated that, depending on her tax bracket at forgiveness, she might owe anywhere from $8,000 to $15,000 in federal taxes on the forgiven amount under IBR, compared to a somewhat smaller liability under SAVE.

That doesn't erase the benefit of forgiveness. But it does shrink the gap between "what gets forgiven" and "what you actually keep." A planner that accounts for estimated tax liability gives a more honest picture than a calculator that only shows the headline forgiveness number.

When IBR Might Actually Make More Sense

I want to be fair here. SAVE looked like the clear winner for Marisol, but that doesn't mean it's the right choice for everyone. The planner helped us see situations where IBR could come out ahead.

If a borrower expects their income to rise significantly over the first five to seven years of repayment — say, someone finishing a medical residency or a law clerk about to move into a firm role — the higher discretionary income threshold under SAVE (225% of poverty) matters less. At a certain income level, both plans calculate payments that exceed the standard 10-year amount, and the borrower might as well just use the standard plan.

But IBR has one feature SAVE doesn't: a payment cap. Under IBR, your payment is never higher than the standard 10-year repayment amount, regardless of how high your income climbs. SAVE has no such cap. For high earners, that makes IBR a safety valve.

IBR is also available to more borrowers in terms of loan types, and it has a longer track record. Some borrowers feel more comfortable with a plan that has existed for years rather than one that has undergone multiple revisions and legal challenges.

The planner let us test a "what if Marisol's income doubles" scenario. Under that projection, IBR's payment cap kept her monthly cost lower than SAVE once her salary passed about $95,000. That's a real insight — not a guess.

What to Look for in a Student Loan Payment Planner

Not every tool calling itself a "planner" actually does what Marisol needed. Most calculators on loan servicer websites show a monthly payment and maybe a total payoff number. That's a starting point, not a plan.

Here's what made the planner we used actually useful:

• Month-by-month projections: Not just a final number, but a timeline showing how balance, payment, and interest change each year.
• Unpaid interest tracking: The ability to see whether interest is being waived, capitalized, or paid down each month.
• Side-by-side plan comparison: Running multiple scenarios simultaneously so the differences are visual, not theoretical.
• Income growth modeling: Letting you input raises, promotions, or career changes to see how payments shift over time.
• Tax liability estimates: Factoring in the potential tax bomb on forgiven amounts so the "total cost" number is honest.
• Forgiveness timeline clarity: Showing exactly when forgiveness kicks in and how much is left at that point.

If your tool doesn't do most of these things, you're getting an estimate — not a plan. There's a difference.

What Marisol Decided (and Why)

After running both scenarios and testing income growth projections, Marisol chose SAVE.

Her reasoning was practical. She's a school counselor. Her salary increases are tied to a district pay scale, not commission or equity. She doesn't expect her income to jump dramatically in the next decade. The interest subsidy under SAVE meant her balance wouldn't grow, her monthly payment would stay manageable, and her total out-of-pocket cost over 20 years would be less than half of what she'd pay under IBR.

She also liked that SAVE's 225% poverty protection gave her more breathing room if she had a low-income year — say, if she took a leave of absence or switched to part-time. Under IBR, her payment would still be calculated against a smaller income protection threshold, meaning a higher payment even during lean years.

The planner didn't tell her what to do. It gave her the information to decide for herself. That's the whole point.

The Bottom Line

A student loan payment planner won't change your interest rate or your balance. But it will change what you understand about your loans — and understanding is what separates a borrower who guesses from one who decides.

For Marisol, the difference between SAVE and IBR wasn't $20 or $30 a month. It was $27,000 in total payments over 20 years, a balance that either stayed flat or grew by $15,000, and a forgiveness event that either felt manageable or came with a tax surprise. That's not a marginal difference. That's a life-altering one.

If you're choosing between SAVE and IBR — or any income-driven plan — don't rely on a calculator that only shows your next monthly payment. Use a planner that shows the next 20 years. Run both scenarios. Look at the interest. Look at the balance trajectory. Look at the tax implications. Then decide.

The numbers will tell you the truth. You just have to give them enough room to speak.