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529 Plans: Time Value of Money, Applied to Tuition

📅 Last Updated: July 2026 ⏱ 5 min read ✦ Get Rich Slow By Michael Azzolina · CPA · MBA
Quick Answer

A 529 plan is a tax-advantaged account for education costs. Contributions grow tax-free and withdrawals are tax-free too, as long as they're used for qualified expenses like tuition, room and board, and books. Starting the day a child is born matters more than the amount you start with, since college is typically 18 years away, and that's a long runway for compounding to do the heavy lifting.

We set up 529 plans for our kids around the same time we handled the will, the trust, and the term life insurance. Of everything in that list, the 529 is the one where timing does most of the work. It's compound interest, applied to a specific bill that's coming whether you're ready or not.

What a 529 actually is

A 529 plan is a tax-advantaged account built for education costs. Contributions grow tax-free, and withdrawals are tax-free too, as long as they're used for qualified education expenses: tuition, room and board, books, and a range of other costs. You're not taxed on the growth, which is the whole advantage over just saving in a regular account.

When we set ours up, we looked specifically at what tax benefit our own state offered, since that varies quite a bit depending on where you live. Some states give you a deduction on contributions, some don't, and the rules change. The broad rule holds regardless of your state: put in as much as you comfortably can, as early as you can. Getting the exact contribution amount right on day one matters far less than giving the money as many years as possible to compound.

Why starting the day a child is born matters so much

College is typically 18 years away from birth. That's a long runway for compounding to do the heavy lifting, which means the amount you need to contribute monthly is smaller the earlier you start. Wait until a child is 10, and you have 8 years instead of 18, so the same goal requires a much larger monthly contribution to reach the same result.

Illustrative: reaching ~$100,000 by age 18, at 7% average return
Starting at birth (18 years to grow)~$220/month
Starting at age 10 (8 years to grow)~$780/month

Illustrative only, assuming a consistent 7% average annual return. Actual returns vary and are not guaranteed. Contribution amounts needed will differ based on your actual goal and timeline.

The same goal costs roughly 3 to 4 times as much per month if you start 8 years late. Feeling behind isn't the point. Starting today is.

Starting small still counts

A 529 doesn't need to be funded with a large amount to be worth opening. Even a modest monthly contribution, started early, benefits from the same long runway. The account being open and growing matters more than the size of the first contribution.

Flexible, not just for a 4-year degree

529 funds can be used for a range of education paths: 4-year colleges, community college, trade and vocational schools, and some can be rolled over for a sibling's use if the original beneficiary doesn't need all of it. It's worth checking current rules, since they've expanded over the years, but the core idea holds: a flexible, tax-advantaged way to prepare for a cost you know is coming.

The takeaway

A 529 plan works the same way every compounding account works: time does most of the job. Starting the month a child is born, even with a modest amount, requires far less monthly effort than starting years later to hit the same goal. The best time to open one is now, whatever "now" is for you.

Frequently Asked Questions

What is a 529 plan?

A tax-advantaged account built for education costs. Contributions grow tax-free, and withdrawals are tax-free too, as long as they're used for qualified education expenses: tuition, room and board, books, and a range of other costs. You're not taxed on the growth, which is the entire advantage.

When should I start a 529 plan?

As early as possible, ideally the day a child is born. College is typically 18 years away from birth, which is a long runway for compounding to do the heavy lifting. Wait until a child is 10 and you have 8 years instead of 18, so the same goal requires a much larger monthly contribution to reach the same result. Starting small still counts, since the timing matters more than the initial amount.

Do I get a tax benefit for contributing to a 529 plan?

It depends on your state. Some states give you a deduction on contributions and some don't, and the rules vary and change over time. Check what your own state offers when you set one up. The broader rule holds regardless of your state: put in as much as you comfortably can, as early as you can, since giving the money more years to compound matters more than getting the exact contribution amount right on day one.