What Happens to Leftover Money in a 529 if the Kid Doesn't Use It All for College?

It stays invested, tax-deferred, and can be moved to another family member’s education or, under current rules, rolled into a Roth IRA for the beneficiary up to lifetime limits. The growth never gets hit with ordinary income tax if it stays inside the 529 for qualified costs.

A 529 is a state-sponsored savings plan. You open it in the parent’s name, name a child as beneficiary, and put after-tax money in. Earnings grow free of federal tax. When you pull money out for tuition, fees, books, room and board, or certain other education expenses, those withdrawals are also free of federal tax. Many states add a deduction or credit on the contribution side if you use their plan. Texas, for example, has no state income tax, so the federal treatment is the whole story there.

There is no federal annual contribution cap. The practical limit is the gift-tax exclusion. In 2026 that is $19,000 per donor per beneficiary, or $38,000 if a married couple elects gift-splitting. You can front-load five years at once—$95,000 for one person or $190,000 for a couple—by filing Form 709 and treating the gift as spread evenly. After that, you wait five years before adding more to the same beneficiary without dipping into the lifetime exemption.

The couple in question is in their early forties, both still working. Combined income sits around $340,000. Husband is a W-2 engineer; wife runs a small consulting practice that nets roughly $90,000 after expenses. They have a 16-year-old and a 12-year-old daughter. Home equity is about $280,000, 401(k) balances total $410,000, taxable brokerage is $185,000, and they carry a modest mortgage plus two car notes. They have term life already in force and no permanent insurance. College is the next big cash need.

Right now they have $42,000 in a 529 for the older kid and $18,000 for the younger one. Both accounts sit in moderate age-based portfolios. The 16-year-old is looking at in-state public universities that currently run about $28,000 a year all-in. Four years would cost roughly $120,000 in today’s dollars, more if inflation keeps grinding. The younger one is still too far out to pin down.

If they keep contributing $1,500 a month split between the two accounts, the older 529 could reach about $75,000 by the time tuition starts in two years, assuming 6 percent average returns and no big market drop. That covers a little more than half of the projected cost. The rest would come from cash flow or the taxable account. For the younger child the same pace would build a larger cushion because there are six more years of contributions and compounding.

They could also superfund. In September they could write a check for $76,000—$38,000 each from gift-splitting—into the older kid’s plan and elect the five-year treatment. That would push the balance near $120,000 almost immediately. The tradeoff is that they cannot put more into that same plan for the next four years without using lifetime exemption, and the money is locked into the 529’s investment menu. If the market drops 20 percent right after the deposit, they have less time to recover before tuition bills arrive.

A common mistake is treating the 529 as the only college bucket. Some families pour every spare dollar in and then discover the kid gets a scholarship or chooses a cheaper school. The leftover can be rolled to a sibling, or up to $35,000 lifetime can move into a Roth IRA for the original beneficiary if the account has been open long enough and the contribution limits are respected. That is useful, but it is not the same as unrestricted cash. Non-qualified withdrawals still face ordinary income tax plus a 10 percent penalty on the earnings portion.

Another friction point is the effect on financial-aid formulas. 529 assets owned by a parent count at a lower rate than student-owned assets, but they still reduce need-based aid. For a family already above $300,000 of income, need-based aid is limited anyway, so the impact is usually small. Merit aid is a different story and does not care about the 529 balance.

What to look at next is straightforward. Run the actual projected cost for the schools the 16-year-old is considering, subtract any likely scholarships, and see the gap. Then decide whether the current contribution rate, a one-time superfund, or a mix of 529 and taxable money closes it with the least opportunity cost. Check the state plan’s fees and investment options against a low-cost national plan if the difference is more than a few basis points. Keep the beneficiary designation current and make sure the account ownership stays with the parents so control does not shift at age 18 or 21.

Numbers here are illustrative and not a recommendation for any specific household.