What is a 529 plan?
A 529 plan is a tax-advantaged account authorized by 
Internal Revenue Code section 529 that helps families save for education costs. States, state agencies, or eligible educational institutions sponsor these plans, and every state plus the District of Columbia offers at least one. Money contributed to the account grows without federal tax as long as withdrawals pay for qualified education expenses, and many states add their own tax break on top. There are two distinct kinds — education savings plans and prepaid tuition plans — and they work quite differently despite sharing the same tax code section. Anyone can open one for a beneficiary, including for themselves, and the Securities and Exchange Commission's Investor.gov is the main federal resource explaining how they function.
Two kinds of 529 plans
An education savings plan is an investment account. The saver contributes money, chooses among investment options such as mutual funds, exchange-traded funds, principal-protected bank products, static portfolios, or age-based portfolios that shift toward conservative holdings as the beneficiary nears college age, and the balance rises or falls with the market. These investments are not federally guaranteed; mutual funds and ETFs can lose money, though some bank products inside a 529 may carry FDIC insurance. A prepaid tuition plan works differently: it lets a family lock in tuition and mandatory fees at current prices, usually for in-state public colleges that participate in the plan. Prepaid plans tend to be less flexible, often carry state residency requirements, are not always guaranteed by the state, and can pay out less than what was put in if the beneficiary attends a school outside the plan's network. Both plan types can be found and compared, along with their official disclosure documents, through the Municipal Securities Rulemaking Board's EMMA website, which houses 529 savings-plan and ABLE-program information.
What the money can pay for
Funds in a 529 education savings plan can cover qualified higher-education expenses, including tuition and certain costs tied to recognized post-secondary credential programs. Beyond college, the same account can pay up to $10,000 per year per beneficiary toward tuition at public, private, or religious elementary and secondary schools, cover registered-apprenticeship program expenses, and repay up to $10,000 total per beneficiary in qualified education loans. Withdrawals that go toward these qualified uses generally avoid federal income tax, and often state income tax as well, though the state tax treatment depends on the specific state and plan. Withdrawals spent on anything else are considered nonqualified: the earnings portion becomes subject to federal income tax plus an additional 10 percent federal penalty, and possibly state tax too. A withdrawal tied to a scholarship the beneficiary received can avoid that 10 percent penalty, though the earnings are still taxed as income.
Costs, contribution limits, and how the tax break works
529 plans charge a range of possible fees: enrollment or application fees, account-maintenance fees, program-management and asset-management fees, sales loads, administrative fees, and redemption or distribution charges. Direct-sold plans purchased straight from the state generally cost less than broker-sold versions, which tack on additional advisor fees, and residents opening their own state's plan may get fee waivers or a state tax deduction that isn't available for an out-of-state plan. Initial deposits are often $250 or less, and plans set their own later contribution minimums, annual state tax-benefit caps, and lifetime contribution ceilings. Contributions themselves count as gifts for federal gift-tax purposes, and account owners can front-load several years of the annual gift-tax exclusion into a 529 in a single year through a special election, though the exact dollar amounts and thresholds should be confirmed directly with the IRS since they're adjusted periodically. Investors are generally allowed to change their investment options within a plan only twice per calendar year, or whenever they change the account's beneficiary.
Changing beneficiaries, and the newer Roth IRA rollover option
A 529 account owner can change the named beneficiary or move funds to a different 529 plan for a member of the same family without triggering tax or penalty, which gives families flexibility if the original beneficiary gets a scholarship, decides against college, or simply has money left over. More recently, federal law added a limited option to move unused 529 funds into a Roth IRA for the same beneficiary. That rollover is capped at $35,000 total over the beneficiary's lifetime, counts against the beneficiary's annual Roth IRA contribution limit for the year of the rollover, and only applies to 529 accounts that have been open at least 15 years, among other conditions. This rollover path is narrow and comes with real restrictions, so anyone considering it should review the current rules directly rather than assume they qualify.
Where to look before opening one
Investor.gov, run by the SEC's Office of Investor Education and Advocacy, publishes a checklist of questions worth answering before opening an account: how the plan's fees compare to others, what investment options it offers, whether the account owner and beneficiary can be changed later, and how the choice between an in-state and out-of-state plan affects both cost and any state tax deduction. It's also worth weighing a 529 against alternatives like Coverdell education savings accounts, UGMA/UTMA custodial accounts, or plain taxable investing, since each has different tax treatment and different effects on financial aid eligibility. None of this is investment advice about which plan or investment option to pick; it only describes how the accounts are structured under federal rules. Families ready to compare specific state plans can search plan disclosure documents through EMMA or start with the SEC's own overview at Investor.gov's 529 plan bulletin.