About

A 529 plan is a tax-advantaged investment account authorized under Section 529 of the Internal Revenue Code. Earnings grow federal tax-free when used for qualified education expenses. The critical variable most families miscalculate is the interaction between r (annual return rate), t (investment horizon in years), and i (education inflation, historically 5% vs. general CPI of 2.5%). Underestimating i by even 1% over an 18-year horizon can create a shortfall exceeding $40,000 for a 4-year public university. This calculator models future value using compound growth with periodic contributions, projects college costs at configurable inflation, and computes state-level tax deductions where applicable.

Note: this tool assumes a constant annual return. Real portfolios experience variance. Age-based allocations shift from equities to bonds as the beneficiary approaches college, reducing average returns in later years. Actual results depend on fund selection, fee ratios (typically 0.10% to 0.70%), and market conditions. Pro tip: many states allow contributions until December 31 to claim the current-year deduction. Check your state deadline.

Formulas

The future value of a 529 plan combines a lump-sum initial investment compounded over time with periodic (monthly or annual) contributions. The general formula:

FV = P ⋅ (1 + rn)^n⋅t + PMT × (1 + rn)^n⋅t − 1rn

Where FV = future value of the 529 account, P = initial lump-sum deposit ($), r = annual rate of return (decimal), n = compounding periods per year (12 for monthly), t = investment horizon in years, PMT = periodic contribution per compounding period.

The projected college cost uses education-specific inflation:

C_future = C_today × (1 + i)^t

Where C_today = current annual cost of attendance, i = education inflation rate (historically 5%), t = years until enrollment. The state tax benefit is computed as: T = min(Annual Contribution, Deduction Limit) × Marginal Tax Rate.

Reference Data

State	Max Deduction (Single)	Max Deduction (Joint)	Top Marginal Rate	Tax Savings (Single, Max)	Notes
New York	$5,000	$10,000	8.82%	$441	Per taxpayer
Virginia	$4,000	$4,000	5.75%	$230	Per account; unlimited if 70+
Colorado	Full amount	Full amount	4.40%	Varies	Full deduction, any plan
Illinois	$10,000	$20,000	4.95%	$495	In-state plan only
Ohio	$4,000	$4,000	3.75%	$150	Per beneficiary
Pennsylvania	$17,000	$34,000	3.07%	$522	Any plan; gift tax limit
Georgia	$4,000	$8,000	5.49%	$220	Per beneficiary
Iowa	$3,785	$7,570	5.70%	$216	In-state plan only
Missouri	$8,000	$16,000	4.95%	$396	Per taxpayer
Indiana	$7,500	$7,500	3.05%	$229	20% credit, max $1,500
Oregon	$3,785	$3,785	9.90%	$375	In-state plan; credit available
Kansas	$3,000	$6,000	5.70%	$171	Per beneficiary
Connecticut	$5,000	$10,000	6.99%	$350	In-state plan only
Wisconsin	$3,860	$3,860	7.65%	$295	Per beneficiary
Michigan	$5,000	$10,000	4.25%	$213	In-state plan only
California	None	None	13.30%	$0	No state deduction
Texas	N/A	N/A	0.00%	$0	No state income tax
Florida	N/A	N/A	0.00%	$0	No state income tax
Washington	N/A	N/A	0.00%	$0	No state income tax
Nevada	N/A	N/A	0.00%	$0	No state income tax

Frequently Asked Questions

Due to compounding, small changes in r produce large differences over long horizons. At 6% annual return with $300/month contributions over 18 years, the balance reaches approximately $116,000. At 8%, it reaches roughly $143,000 - a 23% increase from just 2 percentage points. Conservative age-based portfolios typically average 5 - 7% blended over the full period because equity allocation decreases as the beneficiary approaches college age.

Earnings withdrawn for non-qualified expenses are subject to federal income tax at the account owner's marginal rate plus a 10% penalty on the earnings portion only. The contribution principal is never taxed or penalized since it was made with after-tax dollars. Under the SECURE 2.0 Act (2024), up to $35,000 of unused 529 funds can be rolled into a Roth IRA for the beneficiary, subject to annual Roth contribution limits and a minimum 15-year account age requirement.

College costs have historically risen at 5 - 6% annually versus general CPI of approximately 2.5%. This is driven by labor-intensive cost structures (faculty salaries), administrative growth, capital expenditure on facilities, and reduced state funding for public institutions. The gap means a 4-year public university costing $25,000/year today would cost approximately $60,000/year in 18 years at 5% education inflation.

No. Nine states have no income tax (Alaska, Florida, Nevada, New Hampshire, South Dakota, Tennessee, Texas, Washington, Wyoming), making the deduction irrelevant. Among states with income tax, California, Hawaii, Kentucky, Maine, New Jersey, and North Carolina currently offer no 529 deduction or credit. Some states (e.g., Colorado, South Carolina) allow deductions for contributions to any state's plan, while most restrict the benefit to the in-state plan only. Deduction limits vary from $3,000 (Kansas) to unlimited (Indiana credit-based, Pennsylvania at gift-tax limit).

Monthly contributions result in a slightly lower final value compared to an equivalent annual lump sum invested on January 1, because the lump sum has the full year to compound. However, the difference is modest: on $6,000/year at 7% over 18 years, the annual lump sum yields roughly 3 - 4% more than monthly contributions of $500. Dollar-cost averaging with monthly contributions reduces sequence-of-returns risk and is more practical for most household budgets.

There is no annual federal contribution limit, but contributions are considered gifts for tax purposes. In 2024, contributions up to $18,000 per donor per beneficiary qualify for the annual gift tax exclusion ($36,000 for married couples). A special 529 provision allows 5-year gift tax averaging (superfunding): up to $90,000 ($180,000 joint) contributed at once without triggering gift tax, provided no additional gifts are made to that beneficiary for 5 years. Aggregate state plan limits range from $235,000 to over $550,000.