529 Tax Deduction Calculator
529 state tax saving from contribution and cap.
What it does
529 deductions pay at the state level only, and caps decide how much. Ten thousand dollars at a 5 % state rate saves $500 when no cap binds, while a $12,000 gift against a $10,000 cap still saves $500 on $11,500 net. Rate times deductible amount is the whole game.
The tool above runs cap logic with net and monthly figures. Enter contribution, state cap, and state rate, and it prints saving, net cost, and monthly pace. Defaults show the $500 case; capped and 4.5 % practices show the edges.
Tax authorities draw the boundaries. IRS Publication 970 with Topic 313 denies federal deductions while blessing tax-free growth and qualified withdrawals, and the College Savings Plans Network confirms state deductions and credits vary by home plan. Federal zero plus state maybe is the rule.
Residency chooses the plan that pays. Most deductible states reward own-plan contributions only, so out-of-state shopping forfeits the saving. Confirm caps, carryforwards, and recapture rules yearly; legislatures move them.
How to use
- Enter the annual contribution.
- Enter the state cap.
- Enter the state rate percent.
- Read the saving first, then net cost.
- Read the monthly pace.
- Confirm home-plan rules yearly.
Formula
- contribution
- Annual 529 contribution in dollars.
- cap
- State deductible ceiling.
- rate
- State marginal rate in percent.
IRS Pub 970/Topic 313: no federal deduction, tax-free growth, qualified withdrawals untaxed; CSPN confirms state-level deductions.
Worked example
Example: $10,000 at 5%
Defaults: $10,000 at 5 % with no binding cap.
- Inputs: $10,000 contribution, no binding cap, 5 % state rate.
- Deductible: min(10,000, cap) = $10,000.
- Saving: 10,000 x 0.05 = $500.
- Net: 10,000 minus 500 = $9,500.
- Monthly: 10,000 / 12 = $833.33. Tool shows $500.00, $9,500.00 net.
Reference table
| Gift | Saving | Net |
|---|---|---|
| $10,000 at 5% | $500 | $9,500 |
| $12,000 capped $10k | $500 | $11,500 |
| $6,000 at 4.5% | $270 | $5,730 |
Limits
- State math only. Federal deduction is zero.
- Caps and recapture vary by state.
- Assumes eligible filer in the plan state.
- Earnings rules simplified to contributions.
Common mistakes
- Claiming federal deductions.
- Ignoring the state cap.
- Funding out-of-state plans for deductions.
- Skipping carryforward rules.
- Forgetting recapture on nonqualified moves.
Try it yourself
Quick checks. Answers sit tucked under each question.
$12,000 gift, $10,000 cap, 5 %?
Deductible min(12,000, 10,000) = 10,000. Saving $500. Net $11,500. Monthly $1,000.
$6,000 at 4.5 %, no cap?
Deductible $6,000. Saving 6,000 x 4.5 % = $270. Net $5,730. Monthly $500.
Questions
How is the saving figured?
Deductible amount times state rate. Here $10,000 x 5 % = $500.
What if contributions pass the cap?
State caps bind first: min($12,000, $10,000) x 5 % = $500 on $11,500 net.
Is there a federal deduction?
Zero federally per IRS Topic 313. Only state plans pay deductions or credits.
What is the real 529 benefit?
Earnings grow tax free with qualified withdrawals untaxed federally for higher education.
Do caps and plans vary?
Yes. Many states cap deductions and limit them to own-plan contributions; check the home plan.
What is the monthly pace?
Yes. Monthly is contribution over 12: $833.33 here.
Sources
- IRS Publication 970: QTP Rules (no federal deduction)
- IRS Topic 313: QTPs (state plans, tax-free growth)
- 529 Network (CSPN): State Benefits and Comparisons