Methodology and Sources
How 529PlanCalculator.com sources every contribution limit, state tax deduction figure, plan attribute, and projection on the site. This page documents the primary federal and state sources, the in-scope / out-of-scope boundary, the calculation framework, the monthly refresh cadence, and the limitations of the projection engine.
Last full source pass: July 2026
Section 01. Primary and named sources
Every figure on the site traces to one of the sources below. Where a figure originates in IRS guidance or federal statute, that is the primary source. Where a figure is state-specific (deduction limits, expense ratios, maximum account balance), the state plan administrator's own disclosure document is the primary source. Aggregators (CSPN, SavingForCollege, Morningstar) are used only as cross-references and for ratings.
| Source | Refresh cadence | What we take from it |
|---|---|---|
| IRS Publication 970 (Tax Benefits for Education) | Annually; re-read at each site review | Federal qualified-expense rules, K-12 limit, room-and-board allowance, scholarship interaction, non-qualified withdrawal penalty math, beneficiary change rules. |
| IRS Form 709 instructions | Annually | 5-year gift-tax election (superfunding), annual gift exclusion ($19,000 in 2026), election filing mechanics. |
| SECURE Act 2.0 (Public Law 117-328) | As-needed for implementing regulations | 529-to-Roth IRA rollover rule: $35,000 lifetime limit, 15-year account age, annual cap tied to Roth IRA limit, beneficiary earned-income requirement, 5-year contribution exclusion. |
| One Big Beautiful Bill Act (OBBBA), Sec. 70402 | As-needed for IRS / state conformity rulings | K-12 annual limit increase from $10,000 to $20,000 (effective for distributions after December 31 2025). Expanded K-12 qualified expenses (tutoring, curriculum materials, online education, standardized test fees, dual-enrollment, disability therapies) and postsecondary credentialing-program qualification took effect for distributions made after July 4 2025 (date of enactment). |
| FAFSA Simplification Act (Federal Student Aid) | Annual FAFSA cycle | Parent-asset assessment rate (5.64%); elimination of grandparent-distribution student-income treatment; parent vs student account-owner asset categorisation. |
| College Savings Plans Network (CSPN) | Quarterly review; annual rules cross-check | Per-state plan database (cross-reference): plan administrator names, deduction or credit type, deduction limits, maximum account balance, federal-school-code coverage. |
| SavingForCollege.com (per-state pages) | Lead-finding only | Independent cross-reference for per-state deduction or credit math, plan-administrator changes, and 5-cap-rating comparisons. Not the primary source for any figure; used as a sanity check. |
| Morningstar 529 Plan Ratings | Annual Morningstar rating cycle (late October / early November) | Gold / Silver / Bronze / Neutral / Negative plan ratings; Morningstar Process / People / Parent / Price / Performance sub-pillar coverage. Used in the /best-529-plans rankings. |
| College Board, Trends in College Pricing and Student Aid 2025 (Table CP-1) | Annual (November) | 2025-26 average published tuition, fees, housing and food for public four-year in-state ($25,850), out-of-state ($45,780), private nonprofit four-year ($60,920) and private nonprofit doctoral ($72,420) colleges: the cost bases of every projection on the site. |
| Named state 529 plan administrator pages | At each site review and on plan-revision dates | Plan disclosure documents for Utah my529, Nevada Vanguard 529 College Savings Plan, NY 529 Direct, California ScholarShare 529, Virginia Invest529, Indiana529 Direct, Illinois Bright Start, Colorado CollegeInvest, Pennsylvania PA 529, Massachusetts U.Fund, and every other state's direct-sold plan. Source for maximum account balances (each linked per state on the contribution limits page), fees and investment menus. |
Section 02. In scope and out of scope
In scope
- Federal 529 rules: annual gift exclusion, superfunding, qualified expenses, K-12 limit, apprenticeship and credentialing eligibility, rollover rules.
- State 529 plans: tax-benefit type (deduction or credit, in-state-only or any-state), deduction or credit limit, and maximum account balance, each from the state's or plan's own documents.
- Per-state estimated annual tax savings at one representative state marginal income-tax rate (deduction-style states) or the published credit math (Indiana, Vermont, Utah, Oregon, Minnesota).
- SECURE Act 2.0 529-to-Roth rollover mechanics.
- OBBBA 2026 K-12 expansion and credentialing-program eligibility (federal-level; state conformity flagged where uncertain).
- FAFSA 529 asset treatment under the FAFSA Simplification Act.
Out of scope
- Individual financial-planning advice (consult a qualified tax professional or financial advisor).
- Plan-by-plan investment menu performance attribution (use Morningstar or the plan's own performance reporting).
- Detailed brokerage-account comparisons (only enough to illustrate the relative tax treatment).
- State legislative bills not yet enacted; only signed federal and state law is treated as authoritative.
- Estate-planning interactions beyond the gift-tax superfunding mechanics.
- Pre-paid tuition plans (the calculator covers savings-style 529s only).
Section 03. Calculation framework
The calculator engine and the per-state tax-savings tables are built from the six formulas below. Where a default input is supplied, the user can override it in the calculator UI.
Tuition projection
Annual cost in year Y = College Board 2025-26 published price for the institution type x (1.04)^(Y - 2025). The 4% is our planning assumption, not a College Board forecast: College Board reports a 3.7% (public) to 4.1% (private nonprofit) rise from 2024-25 to 2025-26 in the same table, and a 7% fall in inflation-adjusted in-state public tuition and fees over 2015-16 to 2025-26. The four-year cost adds four consecutive years from the enrollment year, 18 - child_age years after 2026-27.
Investment growth
Future balance = sum of (monthly_contribution x ((1 + r/12)^(months_to_enrollment - month_index) - 1) / (r/12)) over the contribution horizon, plus any opening balance compounded forward. Default r = 7% nominal (long-run S&P 500 real return + inflation anchor). Conservative vs marketing “average return” figures.
State tax savings
Deduction-style states: annual_savings = min(annual_contribution, deduction_cap) x median_marginal_rate. Credit-style states (Indiana 20%, Vermont 10%, Utah 4.45%, Oregon, Minnesota): savings calculated from the published credit formula and credit cap, not from the marginal rate. Joint-return caps use each state's own joint figure. The 8 any-state-deduction states (AZ, AR, KS, ME, MN, MO, MT, PA) are flagged separately because a low-fee out-of-state plan can be used while still claiming a state deduction.
Superfunding (5-year election)
$19,000 annual exclusion x 5 = $95,000 single (or $190,000 married) front-loaded in year 1, with IRS Form 709 filed to elect the 5-year gift-tax spread. No additional contributions to the same beneficiary during the 5-year window without triggering gift-tax filing.
529 to Roth IRA rollover (SECURE 2.0)
$35,000 lifetime limit per beneficiary; 529 account must be open at least 15 years; annual rollover capped at the Roth IRA contribution limit ($7,500 standard in 2026; $8,600 with the age-50 catch-up); contributions and earnings from the last 5 years excluded from eligible rollover amounts; beneficiary must have earned income at least equal to the rollover.
FAFSA impact
Parent-owned 529: counted as parent asset, max 5.64% assessment rate. Student-owned 529 with parent as account owner: also treated as parent asset (5.64%), not student asset (20%). Grandparent-owned 529 distributions: no longer counted as student income (post-2024 FAFSA Simplification Act), removing the previous “grandparent loophole” downside.
Section 04. Refresh cadence
The site is reviewed against its sources periodically and whenever a source publishes a change. A review re-reads federal limits in the IRS revenue procedures and Publication 970, and state deduction rules and plan maximum balances in each state's or plan's own documents. Aggregator sites are used only to find leads, never as the source of a figure.
Each page's “Updated” date and schema dateModified come from the date its content last changed, computed when the site is built, so a page is never re-dated without a real edit. The “data verified” label is separate and moves only when the figures are re-checked.
Events that trigger a review:
- IRS Publication 970 revision or mid-year guidance notice on 529 rules.
- State 529 plan administrator change (plan manager, expense ratio, deduction cap).
- OBBBA or SECURE Act 2.0 implementing regulations from Treasury or IRS.
- Annual College Board Trends in College Pricing release (November).
- Annual Morningstar 529 plan rating cycle (late October / early November).
Section 05. Limitations
- Calculator outputs are projections, not guarantees. The default 7% nominal return and 4% college cost growth are stated assumptions; actual investment returns and tuition cost can deviate substantially in any individual year or 18-year window.
- State 529 plan rules drift between refresh cycles. Plan administrator pages occasionally publish revisions, fee changes, or investment-menu updates mid-cycle; out-of-cycle triggers exist for material changes but minor revisions may lag until the next review. Many plans raised their maximum balances in 2026, and some plan FAQ pages still show old limits; the program description or its latest supplement is the authority.
- OBBBA state-conformity is uneven. Some states have not yet conformed to the federal K-12 limit increase or the expanded qualified-expense list. The site flags state-conformity uncertainty where known, but states can change conformity mid-year and there can be a lag before the site reflects it.
- Per-state “estimated annual tax savings” uses median state marginal income-tax rates for deduction-style states. A taxpayer in a higher bracket than the median will save more; a lower-bracket taxpayer will save less. The figures are planning anchors, not personal tax calculations.
- The 529-to-Roth rollover rule is still being implemented; some custodian operational details (paperwork, beneficiary verification, 5-year exclusion handling) may not be uniform across providers. Verify with the receiving Roth IRA custodian before initiating a rollover.
Section 06. Corrections process
If you spot an out-of-date limit, a state rule that has been revised since the last refresh, a broken link to a plan administrator, or a math error in the calculator, email [email protected]. Substantive corrections are reviewed within five business days, applied to source, and noted in the next monthly refresh stamp. See the about page for the full editorial position and disclosures.