Recently, I’ve noticed that a lot of people ask: how old do you have to be to start trading stocks? Actually, this question is a bit more complicated than you might think.

To start with the conclusion: if you want to fully have control over opening an investment account, in the U.S. you must be at least 18 years old. But that doesn’t mean you have to wait until 18 to start investing—many minors already begin laying the groundwork through a guardian account.

I’ve noticed that many young people don’t realize this: the earlier you start investing, the more terrifying the power of compound interest becomes. For example, if you’re 20 years old and invest 1,000, by the time you’re 60 it could become 10 times, 20 times, or even more. But if you only start at 30, that growth potential shrinks dramatically. This isn’t some inspirational cliché—it’s real mathematics.

For minors, there are mainly a few account options. A joint account (Joint Account) is the most flexible—you and your guardian jointly own it, and you can participate in investment decisions. Many brokers support this setup. For instance, Fidelity has a dedicated Youth Account: teenagers aged 13–17 can use it, and the minimum to buy stocks or ETFs is as low as 1 dollar.

Another option is a custodial account (Custodial Account). In this case, the minor is the nominal owner of the assets, but the guardian holds the decision-making power. When you reach the legal age (usually 18 or 21), you get full control. These accounts also come with tax benefits, which can be quite worthwhile for young investors. Apps like Acorns offer this service, and the monthly fees aren’t expensive.

Another option is a custodial IRA (Custodial IRA). If you have earned income (for example, a summer job, tutoring, etc.), you can open a Roth IRA. The contribution limit for 2023 is 6,500 dollars. Using a Roth when you’re young is especially smart, because your tax rate is low now. Once you lock in that low tax rate for growth, your earnings are completely tax-free—an advantage that can last for decades.

As for what to invest in, young people should generally lean toward growth-oriented assets. Individual stocks, funds, and ETFs are all worth considering. If you don’t want to take the risk of going all-in on a single stock, index funds are a good choice—diversification reduces risk, and costs are also low.

Honestly, I’ve seen too many people regret not starting earlier when they hit their 30s. When you’re young, every dollar grows larger in value because there’s enough time for compound interest. And if you develop an investing habit early on, in the long run, that kind of discipline can have a huge impact on your life’s financial situation.

So instead of asking how old you have to be to invest, ask yourself: why haven’t I started yet?