For millions of Americans, the tax filing process mostly comes down to clicking "next" a bunch of times. Same address? Same employer? Roughly the same income? Check, check, check.

Unless you had a major life event, such as a marriage, the birth of a child or a home purchase, you may find your tax return looking very similar to last year's. But before you click "file," make sure you're not overlooking key documents. Some forms that may not have been on your radar last year could drastically raise or lower your bill for tax year 2023, experts say.

One in particular might take you by surprise, says Ed deHaan, an accounting professor at the Stanford Graduate School of Business.

"People might not realize that interest on a high-yield savings account — which is essentially new in 2023 — is taxable at your wage rate, and banks don't withhold tax on that," he says. "So if you're one of these people with three months' income sitting in a cash account somewhere, you're going to get billed for that."

Here are three tax documents you may have forgotten about last year that could be important this tax season.

1. 1099-INT for savings accounts

You always owed federal income tax on interest from savings accounts. But as deHaan points out, what makes this "essentially new" is that, thanks to rate hikes from the Federal Reserve, some accounts have finally begun paying respectable interest rates.

"If you were fortunate and had $100,000 sitting in your account that's paying 5%, you've made $5,000," he says. "If your marginal rate is 50%, you're paying $2,500 on that, in April."

Even if you earned substantially less than that, you're supposed to report it. Generally, your financial institution will send you a Form 1099-INT when you earn more than $10 in interest.

If you've already filed and have the document sitting in your inbox, don't sweat it too much. If it's a tiny dollar amount, the IRS likely won't be sending auditors your way, says Mark Jaeger, vice president of tax operations at TaxAct.

Even if you forgot to report a chunk of your interest income, "the main story is not to panic. The IRS is used to that happening all the time," Jaeger says. "If you already filed, get your refund. Once you do, you can e-file an amended return."

2. 1099-MISC or 1099-B for crypto profits

The IRS began asking about digital assets, such as cryptocurrency, in 2019. The language in 2023: At any time during 2023, did you: (a) receive (as a reward, award or payment for property or services); or (b) sell, exchange, or otherwise dispose of a digital asset (or a financial interest in a digital asset)?

For 2023, you must answer "yes" if you sold crypto; traded one coin for another; or received digital currency as a payment, reward or award, according to Form 1040 instructions. You could answer "no" if you bought crypto with U.S. dollars and still hold the asset.

Even if you sold some crypto in 2022, this likely didn't feel like a pressing question. After all, with prices on digital assets plummeting, it became less and less likely that investors would have turned a profit.

But with popular cryptocurrencies hitting new highs, it's worth remembering that any profit you realized from selling crypto is taxable at either the short- or long-term capital gains rate, depending on how long you held it.

For 2023, you may receive a Form 1099-MISC or 1099-B from the financial institution you use to trade crypto. You may receive no form at all, which makes life especially challenging for frequent traders, Matt Metras, an enrolled agent owner of MDM Financial Services, told CNBC.

"Once you have more than five transactions, trying to do it yourself in an Excel spreadsheet becomes overwhelming," he says.

3. 1098-E for student loan interest

After a years-long government-mandated forbearance, interest on federal student loans began accruing again in September.

Borrowers don't have much reason to celebrate that fact, but one silver lining is that many can claim a tax break they'd all but forgotten about. The student loan interest deduction allows qualifying borrowers to deduct up to $2,500 a year in paid interest on eligible private and federal student debt.

That means you may have four months' worth of payments from the end of 2023 with deductible interest. That can be worth up to $550, depending on your tax bracket and the amount of interest you paid, higher education expert Mark Kantrowitz told CNBC.

To file for the deduction, look for Form 1098-E, which your student loan servicer may issue by mail or on their website.

And unlike many tax breaks which require filers to itemize deductions, the student loan deduction is "above the line."

"That means you can deduct your student loan interest, even if you're taking the standard deduction," says Jaeger.

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