Tax season officially began on Jan. 27 when the Internal Revenue Service started accepting returns, and chances are you haven't gotten around to it yet.

That's fine; no one expects you to get up that morning and run downstairs to find your calculator and little green visor. Doing your taxes isn't fun, and you have until April 15 to get it done.

But 31% of Americans say they're procrastinating on preparing a return, according to financial services company IPX1031 — and tax experts say they're making a big mistake. That's because, whether you expect a refund or a bill, getting a surprise close to the deadline is rarely a smart move, says Ryan Losi, a certified public accountant and executive vice president with Piascik.

"It's always nice to be able to have it buttoned down early," he says. That way, you know "where you're going to land."

What's more, filing early reduces the chances that criminals can file a return in your name to claim your refund for themselves — a form of fraud that would be devastating for millions of Americans. Nearly 4 in 10 taxpayers rely on their refund to make ends meet, according to a recent survey from Credit Karma.

But even if you're in good shape and not worried about fraud, here's why getting a start on your taxes early this year is likely a smart move.

You can prepare if you owe

For many younger Americans, procrastinating on taxes comes from a fear of the unknown. Among Gen Z filers who wait until the last minute, 26% say its because they don't want to know what they owe, according to a recent survey from Credit Karma.

To an extent that's understandable. Having a potential, amorphous bill looming can be scary, especially if money is tight. But putting a dollar figure on what you may owe as early as possible is the best way to deal with it, says Courtney Alev, head of tax and consumer financial advocate at Credit Karma.

"If you wait to the last minute and you're actually getting a big tax bill instead of a refund, the deadline is there, and it's coming, and you haven't made a plan for how you're going to address that," she says.

If you prepare your taxes ASAP and find out that, indeed, you owe the IRS, you have until April 15 to make a plan, says Losi.

"Maybe you have enough set aside to pay it," he says. "But if you don't, now you can spend the next two months saving some of your paycheck in order to pay it."

You can get your refund sooner

If you had your employer withhold too much of your pay for taxes throughout the year, you can expect a refund when you file. And for many Americans, that's a big deal.

Not only do 37% of filers say they rely on their refund to make ends meet, but 47% plan to use their refunds to pay down debt, according to Credit Karma. In other words, millions of Americans rely on their refund to reach important financial goals. Delaying that refund could have negative ramifications, says Alev.  

"If you're putting off filing, it could put some of your other goals, like paying off your credit card, at risk," she says.

And even if you don't need the money urgently, you're better off having your refund and putting it to use than letting the government hang onto it without paying you any interest. Simply put: the sooner the file, the sooner that refund money hits your bank account.

You know which documents you need to gather

Just because you start the process of preparing your taxes early doesn't mean you have to file them right away. There are certain taxpayers for whom it makes sense to wait awhile.

If you have a brokerage account that earned dividend income or through which you realized a capital gain this year, for instance, you may not be ready to file yet, says Losi.

"You're going to have to wait for that brokerage statement to come in, which will likely come in early March," he says.

The same principle applies to trust beneficiaries and owners or investors in any type of passthrough entity, such as an S-corporation, who will have to wait for their Form K-1 to arrive before filing.

But even for those people, Losi recommends at least getting the ball rolling by plugging some estimates into your tax preparation software. Plus, you'll know which documents you need to have handy when you do file.

"You want to at least have your numbers together early — then you can decide when to actually file," he says.