The catch: state rules vary wildly. New York gives you up to $10,000/yr deduction. Illinois gives you $20,000/yr. California gives you $0. And most states require you use THEIR plan to get the deduction (8 states let you use any 529).
Pick your state below — the calculator shows your annual deduction, lifetime tax-free growth, and total benefit.
no state deduction
Your state has no 529 deduction or credit — but tax-free federal growth still applies.
$
Used to project lifetime tax-free growth.
California doesn't offer a 529 state tax deduction or credit.
You still get the federal benefit (tax-free growth on contributions used for education). Over 15 years at 6% growth, that's about $12,414 saved in federal capital gains tax. Since there's no state benefit, shop around freely — most state plans accept out-of-state savers, so compare the expense ratios they publish and pick a low-cost index option.
15-year projection at 6% annual growth
Total contributed
$150,000
Account value
$232,760
Tax-free growth
$82,760
Walkthrough
A concrete example, step by step
Meet the Patels. Two kids (ages 3 and 5), live in Illinois, filing married. They contribute $20,000/year to Illinois's BrightStart 529. Here's what they get versus the family next door who skips the 529.
Without 529 (regular brokerage)
- Contribute $20k/yr to a regular taxable brokerage for 13 years.
- No state deduction — full $20k goes in, no tax break.
- Grows to ~$400,000 (~$140k of growth).
- When sold for college: pay 15% LTCG on the $140k = $21,000 federal tax.
- Net for college: ~$379,000.
With 529 (Illinois BrightStart)
- Contribute $20k/yr — fully deductible on IL state return.
- Save 4.95% × $20k = $990/yr in IL state tax.
- Grows to ~$400,000 (~$140k of growth).
- Withdrawn for tuition: $0 federal tax on the $140k growth.
- Net for college: ~$400,000 + $13,000 in state tax saved.
The total advantage: ~$34,000 over 13 years — roughly the cost of one year of in-state tuition. Same dollars saved either way, just routed through the 529 wrapper.
The Patels' only "homework" was opening the IL plan once and setting up automatic monthly contributions. Total time: 30 minutes. Total benefit: a free year of college.
Questions
Frequently asked questions
What is a 529 plan?
A 529 plan is a state-sponsored savings account specifically for education. You put money in (after federal tax — there's NO federal deduction), it grows tax-free, and when you pull it out for qualified education expenses (tuition, room/board, books, even K-12 school costs up to $20,000/year), you pay ZERO tax on the growth. So if you put in $50,000 and it grows to $150,000 over 18 years, you keep all $100,000 of growth tax-free. It's basically a Roth IRA for education. The bonus: many states give you a STATE-level tax deduction or credit for contributing to their plan — a yearly benefit on top of the tax-free growth.
Walk me through it with real numbers.
Meet the Patels. Two kids (ages 3 and 5), live in Illinois (one of the most generous 529 states), filing married. They contribute $20,000/year to Illinois's BrightStart 529. RIGHT NOW: they get a $20,000 deduction on their Illinois state return. At Illinois's 4.95% flat rate, that saves them $990/year in state tax. OVER 13 YEARS until the older kid hits college: contributing $20k/year at 6% growth = ~$400,000. About $140,000 of that is growth — completely tax-free when used for tuition. Compared to investing in a regular taxable brokerage where they'd pay 15% LTCG on the growth: they save another ~$21,000 in federal capital gains tax. Total benefit over 13 years: ~$13,000 in state tax savings + $21,000 in federal tax savings = $34,000 they would NOT have saved by investing in a regular account.
Does my state give a deduction? How much?
Depends on the state. (1) NO STATE DEDUCTION (4 states with an income tax): California, Hawaii, Kentucky, North Carolina. If you live in these states, the only benefit is federal tax-free growth — still worth it, but no extra state goodies. (2) UNLIMITED DEDUCTION (3 states): New Mexico, South Carolina, West Virginia. You can deduct as much as you put in. (3) A CAPPED DEDUCTION (31 states): between $500 and $39,200 a year. The highest: Colorado at $26,200 single / $39,200 married. (4) 8 states (AZ, AR, KS, ME, MN, MO, MT, PA) let you deduct contributions to ANY state's 529 — so you can use whichever plan has the best investment options. The other 30 states with a state break require you use THEIR plan to get it.
What if my kid doesn't go to college?
Three options: (1) Change the beneficiary to another family member — sibling, cousin, even yourself if you go back to school. The IRS defines 'family member' broadly. (2) Roll up to $35,000 lifetime into a Roth IRA for the beneficiary (rule started in 2024 — has to be a 529 that's been open 15+ years). This basically turns 'unused' 529 money into retirement savings for your child. (3) Take a non-qualified withdrawal — you owe income tax on the GROWTH portion (not your original contributions) plus a 10% penalty on the growth. Annoying but not catastrophic if your alternative was zero. Most families don't actually face the 'unused 529' problem because qualified expenses now include K-12 school costs (up to $20,000/yr), trade schools, and apprenticeships.
Should I use my home state's plan or shop around?
If your state offers ANY tax benefit, use the home state plan — the tax savings almost always outweigh a slightly higher expense ratio. Even a small state credit usually beats shopping for a marginally cheaper out-of-state plan. The exceptions: (a) you live in a state with NO state deduction (CA, HI, KY, NC) — then shop around freely, comparing plans on the expense ratios each one publishes in its current disclosure booklet. (b) You live in a state that allows ANY 529 (AZ, AR, KS, ME, MN, MO, MT, PA) — you get the deduction PLUS your pick of plan. (c) Your home state's plan has an unusually high expense ratio and your state's deduction is small. Then the math sometimes flips.
Is contributing to my own 529 just as good as my parents'?
Yes, sometimes better. The 529 owner gets the state tax deduction, NOT the parent of the beneficiary. So if grandparents contribute $10,000/year to a 529 for their grandchild, the GRANDPARENTS get the state deduction (assuming they're in a state with one). One quirk: the FAFSA financial-aid formula treats parent-owned 529s differently from grandparent-owned 529s. Parent-owned: counted as parent asset (5.6% impact on aid). Grandparent-owned: was historically counted as student income (50% impact!) — but the 2024 FAFSA Simplification Act eliminated this. Now grandparent 529s have ZERO FAFSA impact. So in the post-2024 world, grandparents contributing to their own 529 (instead of giving cash to parents to contribute) is the optimal play.
What expenses count as 'qualified'?
Generous list: tuition (college; grad school; trade schools), required fees, room and board (if enrolled at least half-time — caps at the school's published cost of attendance), books and supplies, computers and internet (yes, really), special needs equipment. K-12 costs up to $20,000 a year per student: tuition, curriculum, books, online materials, outside tutoring, standardized-test and dual-enrollment fees, and educational therapies for students with disabilities. Student loan repayment up to $10,000 lifetime per borrower (added in 2019 SECURE Act). Apprenticeships registered with the Department of Labor. NOT qualified: transportation, health insurance, club fees, sports gear (unless required by the program). If you withdraw for non-qualified expenses, you pay tax + 10% penalty on the GROWTH portion only.
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