Run the Numbers: Does a 529 Actually Pay Off for Your Family?

You’ve stuck around this long, and like most military trainings it’s usually for one of two reasons: it’s a requirement, or you’re waiting for your orders. Personal financial planning covers so many “what-ifs” that are years into the future that it’s impossible to build a plan that works out perfectly. And when it comes to financial education, coaching, counseling — and all the way up to expensive AUM and fee-collecting advising and planning, the range of individual circumstances is so vast that there’s simply never going to be a right answer, or a one-size-fits-all solution.

That can be a hard thing to hear, especially in the military where we’re trained to receive clear orders — and go execute them. In financial planning, and especially for planning future educational expenses, you’ve got to get in the trenches yourself: you need to know your own values and goals and life situation, and be ready to apply financial planning principles to them.

This post is as close as you’ll likely ever get to an executable order. We built an actual calculator that can help you model your situation. It’s not polished up and live just yet, so in beta testing internally we were able to still pull some numbers for a representative military family, and share those in this post.

Two Forces, Pulling Opposite Directions

Everything in the first four posts comes down to a tug of war.

Pulling for the 529: the growth inside it never gets taxed, as long as you spend it on education.

Pulling against it: the balance sitting in that account reduces the financial aid your child can receive.

Both sides get stronger as the account gets bigger, but they don’t pull equally hard at the same time. So the real question isn’t “is a 529 good or bad.” It’s which force wins at your numbers. That’s a calculation, not an opinion, and you can run it yourself.

Let’s build it one side at a time.

Side One: What the Aid Actually Costs You

A parent-owned 529 reduces need-based aid eligibility by up to 5.64% of the balance, every year you file the FAFSA. Remember from Part 4 that even if you give the plan to your child, they are still your dependent and so the reduction is the same 5.64%.

People stop there and think “5.64%, that’s small.” It isn’t, because you file every year and the number stacks up. In other words, it’s 5.64% of the remaining 529 balance each year for four years. Watch a $100,000 account get spent down over four years:

FAFSA filing	Balance	Aid eligibility lost
Freshman year	$100,000	$5,640
Sophomore year	$75,000	$4,230
Junior year	$50,000	$2,820
Senior year	$25,000	$1,410
Four-year total		$14,100

A $100,000 529 Plan costs you about $14,100 in aid eligibility across a four-year degree. Not $5,640. Fourteen thousand. The ratio is the same at any account balance that is stretched equally over four years, from $10,000 to $10 million: the only way to reduce the loss is to burn through the entire account in fewer years.

The shortcut to remember: the total aid cost is roughly 14% of your 529 balance.

Side Two: What the Tax Break Is Actually Worth

Now the other side. What does the 529 save you that a plain brokerage account wouldn’t?

Only the tax on the growth. Your contributions were after-tax dollars either way. So take that same $100,000 account at our standard 45/55 split — $45,000 of contributions, $55,000 of growth — and the question is what you’d have paid on $55,000 of gains in a brokerage instead.

At the 15% long-term capital gains rate: $8,250.

That’s the prize. Eight thousand two hundred fifty dollars.

Now Put Them Side by Side

	Amount
Aid eligibility lost to the 529	$14,100
Tax saved by the 529	$8,250
Net result	−$5,850

If your family actually receives need-based aid, a $100,000 529 Plan costs you about $5,850 more than a brokerage account would have. This is the tradeoff in tax advantage and aid only: if you then need your 529 money for non-qualified expenses, the tax and penalty on your gains will stack on that and make the loss worse.

That’s the whole argument in one table. But there’s a giant “if” in that first sentence, and it’s the thing that decides everything.

The “If”: Do You Actually Get Aid?

Losing $14,100 of aid eligibility only hurts if you were going to receive aid in the first place.

Plenty of families never see a dollar of need-based aid. For them, the aid cost is zero and the 529 wins on tax, easily. Other families are deep in the aid range at a school that covers most of their need. For them the aid cost is the full $14,100 and the 529 loses badly.

So think of it as a dial, not a switch. Call it your aid capture rate: how much of that lost eligibility turns into aid you actually don’t receive. Zero means you were never getting aid anyway. One hundred percent means every dollar of eligibility you gave up was a dollar the school would have handed you.

Here’s the tipping point, and it’s simpler than you’d expect.

The 529 comes out ahead when your aid capture rate is lower than about 1.06 times the growth share of your account.

If you like algebra: the tax benefit is 0.15 × g × B, the aid cost is 0.141 × α × B. Set them equal, resolve, and you get g = 0.94α. That is the engine that drives our calculator.

Since the growth share depends on how long you’ve been contributing and assumes average annual real returns of 8%, that gives you a table you can actually use:

Years contributing	Growth share of balance	529 wins if aid capture is below
6 years	22%	23%
10 years	34%	36%
15 years	48%	51%
18 years (birth to college)	55%	58%
25 years	68%	73%

The headline: a 529 funded from your child’s birth needs the school to cover less than about 58% of your demonstrated need in order to beat a brokerage account at its own game.

And look at the top row of that table. At a school that meets 100% of demonstrated need, you’d need a 94% growth share to break even, or roughly 55 years of compounding — hint: reason #2 to do it for the grandchildren and not your own kids. At a full-need school, the 529 loses every time. Period.

Worked Example: 529 Clearly Wins

Meet a dual-income O-6 household.

The O-6 has 26 years in, earning $15,188.70 a month in base pay — about $182,264 a year. The spouse earns $55,000. Remember, BAH and BAS aren’t taxable.

Household AGI: about $237,264. Standard deduction for married filing jointly in 2026 is $32,200, so taxable income is roughly $205,000.

Their daughter chooses an in-state public university. Average total cost of attendance at a four-year in-state public runs about $30,990 a year to cover tuition, fees, housing, food, and books, all in.

Do the math the FAFSA does. This family’s expected contribution will land far above $30,990. There is no demonstrated need. No need means no need-based aid, which means no aid to lose.

Aid capture rate: zero. Aid cost: $0. Tax benefit: $8,250.

For this family at this school, the 529 Plan is a clear winner. Fund it.

Worked Example Two: Same Family, Different School

Now the daughter gets into Caltech.

Caltech’s total cost of attendance is about $93,912 a year, and Caltech commits to meeting 100% of demonstrated financial need.

Our family will show real demonstrated need. Call it roughly $29,000 a year of need after their expected contribution. That’s genuine aid money, and Caltech is committed to meeting all of it. Which means the aid capture rate here isn’t zero. It’s close to 100%.

	Public university	Caltech
Cost of attendance	~$30,990/yr	~$93,912/yr
Demonstrated need	None	~$29,000/yr
Aid capture rate	~0%	~100%
Aid cost of a $100,000 529	$0	$14,100
Tax benefit of the 529	$8,250	$8,250
Net	+$8,250	−$5,850

Same family. Same $100,000. Opposite result.

Notice what changed: not their income, not their savings discipline, not the account. Only the school. And that’s a decision an eighteen-year-old makes, years after you locked the money up.

That’s the honest planning principle here. If your child is headed to a public university and your household income is comfortable, the 529 is a solid tool. If there’s a real chance of a high-cost, meets-full-need private school, the 529 can quietly cost you thousands.

The Other Half: You May Owe 0% Anyway

Now here’s the part that reframes everything, and it’s the piece almost no civilian article will tell you, because it depends on how military pay works — which determines a totally different tool is actually better at the 529’s job than the 529 is: the brokerage. And the reason is the tax treatment: 529 gains are taxed like ordinary income, like your paycheck, while brokerage gains are treated as capital gains at much lower rates.

Long-term capital gains in 2026 are taxed at 0% up to $49,450 of taxable income for single filers and $98,900 married filing jointly. Not gross income. Taxable income, after your deductions.

Military families sit in that zero bracket far more often than civilians do, for one reason: BAH and BAS aren’t taxable. A family with a comfortable standard of living can still have modest taxable income.

Watch how far up the rank structure this reaches. Take a single-income household, married filing jointly, taking the standard deduction:

Rank	Approx. base pay	AGI	Taxable income	Room left in the 0% bracket
E-6 over 10	~$57,000	$57,000	~$24,800	~$74,100
E-7 over 20	~$68,400	$68,400	~$36,200	~$62,700
O-3 over 6	~$94,000	$94,000	~$61,800	~$37,100
O-4 over 18	~$117,350	$117,350	~$85,150	~$13,750

Read that bottom row carefully. An O-4 with eighteen years — a fairly senior officer — can still realize $13,750 of long-term capital gains and pay zero federal tax on them. Everyone below that line has more room, not less.

The Head-to-Head That Should Settle It

Put that against a 529 doing its very best work.

You have a $100,000 529 Plan, 45% contributions and 55% growth, and you spend it on college at $25,000 a year for four years. Pro-rata means each withdrawal is $11,250 of contributions and $13,750 of gains. Spent on qualified education, you pay $0 tax on those gains. Perfect execution. Exactly what the account was built for.

Now the same family with a $100,000 brokerage account instead, same investments, same 45/55 split, withdrawing the same $25,000 a year with the same $13,750 of gains.

That O-4 family has $13,750 of room in the 0% bracket.

They also pay $0.

Identical outcome. The 529’s best-case tax benefit — the entire reason to own one — is a benefit this family already has for free, in an account with no restrictions, no penalties, and no FAFSA drag.

And now the part that isn’t a tie. Suppose the child doesn’t go to college. Or they do but with the GI Bill, or they are nominated to a service academy, or attend a trade school; maybe they followed an enlisted-to-commissioning program. Or maybe they joined up out of high school, or got a job or started a business, or simply just changed their mind.

	529 Plan	Brokerage
Withdraw $25,000 (with $13,750 of gains)	Tax at 12%: $1,650	$0
10% penalty on gains	$1,375	$0
Total cost to get your money	$3,025	$0

Same money, same investments, same withdrawal. One costs $3,025 to access and the other costs nothing. And that’s every year, on every withdrawal.

Which leads to a genuine planning principle for a large share of the force: if your taxable income keeps you in the 0% capital gains bracket — and for a single-income military household that’s roughly O-4 and below — a plain brokerage account matches the 529’s best case and destroys it in every other case.

So Where Does That Leave You?

Three situations. Find yours.

Tier 1 — You won’t receive need-based aid, and you’re above the 0% capital gains bracket. Your income is high enough that aid isn’t coming and capital gains cost you 15%. The 529’s tax break is real money and nothing offsets it. 529 is a no-brainer.

Tier 2 — You’re in the 0% capital gains bracket. Roughly O-4 and below on a single military income. The 529’s best-case benefit is something a brokerage already gives you, without the lock-in. The brokerage is simpler and just as profitable, and has none of the back-end exit limits and risks.

Tier 3 — You’ll receive meaningful need-based aid at a school that covers most of it. The aid cost runs about 14% of your balance and the tax benefit maxes out around 8%. The 529 costs you money. If a grandparent is willing to own the account instead, that drag drops to zero (refer again to Part 4).

And one more time, because it’s the whole point of this series: none of these three situations is where most military families actually start. Most start with the GI Bill covering one degree, a state waiver they never inventoried, and no gap at all.

Run the stack first. Then run this math. Then decide.

Next: Final Phase

If you’ve worked through all five posts and a real gap still remains — a second or third child, a private school, graduate work — then the 529 has a job to do in your plan.

Part 6 is the execution: how much to put in, why K-12 spending just became the strongest case in the whole product, how to handle multiple children, and what to do if you’re already sitting on a balance bigger than you can cleanly get back out.

Want to run your own numbers? We built a free 529 calculator specifically for military families that accounts for the GI Bill, your benefits stack, your state, and this aid-versus-tax math. Try it HERE.

This content is educational in nature and does not constitute financial, tax, or legal advice. Tax brackets, aid formulas, and school policies change, and every family’s situation is different — verify your own numbers with a qualified tax professional and the financial aid office of any school you’re considering. You are responsible for your own financial decisions.