Among the many reforms found in the new tax law, one last-minute change allows families to begin using their 529 Plan savings to pay for their children’s K-12 tuition (up to $10,000 per beneficiary, per year). Until now, 529 Plans could only be used to pay for qualified higher education costs.

Since private schooling is expensive, you may be tempted to tap into this new, tax-sheltered funding source as soon as you’re able.

But should you?

The answer is: It depends.

What’s the highest, best use of your 529 plan assets?

The main reason you squirrel away money in a 529 plan is to protect your investments against taxes, and the debilitating effect they have on your end returns. With their tax-preferential treatment, your 529 plan savings are expected to grow bigger and faster than if you held that same money in a taxable account.

Thus it stands to reason, the longer you keep your money invested in a 529 account, the better you’re leveraging its tax-sheltering benefits.

In this context, among the best applications for a 529 plan remains the same as before: to start setting aside money when your kids are in diapers, in anticipation of that bittersweet day they head off to college.

That said, life doesn’t always go as expected. The new K-12 spending allowance may be ideal if you end up with “extra” funds in a 529 plan. For example, what if your firstborn decides to attend an in-state university instead of Harvard? Or what if she earns a full scholarship to her first-choice institution! It may make sense to use up the leftover 529 money on her younger brother’s high school tuition, especially if he already has a fully funded 529 plan of his own.

Where do you live?

There’s an added wrinkle to consider before taking money from a 529 plan for K-12 tuition. As this Forbes article describes, qualified 529 plan withdrawals for K-12 tuition may now be tax- and penalty-free on your Federal tax return (thanks to the 2017 Tax Cuts and Jobs Act). But your state tax laws may differ.

Which brings me back to my initial answer. Should you spend your 529 plan assets on K-12 costs? It depends.