The events of 2021 didn’t always play out as expected. A lingering pandemic, a shifting government response and a wave of career moves meant many people ended the year in a far different place from where they began.

Now, as the income tax filing deadline approaches, those life changes may bring a new wave of surprises for U.S. taxpayers.

If your income changed, or if you made money in the stock and cryptocurrency boom, you may find a larger-than-usual tax bill. If you welcomed a new child or had major medical expenses, you might qualify for new breaks.

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Whatever your situation, it may take longer than you expect to gather information and understand provisions that may not have applied to you before.

“Take nothing for granted. Question everything. Don’t make assumptions, even about your own situation,” says Akeiva Ellis, a certified public accountant and certified financial planner in Waltham, Massachusetts.

Through November, an average of 3.9 million people quit their jobs each month of 2021, according to the Society for Human Resource Management. That’s the highest number since the federal government began publishing the data in 2000.

How a career change affects your taxes depends in part on why you left.

IF YOU GOT A NEW JOB: You’ll get W-2 forms from each employer, and the combined pay reported on those will help you calculate your total income for the year. It’s pretty straightforward, as long as you withheld the correct amount.

IF YOU STARTED WORKING FOR YOURSELF: People who became their own bosses will have to pay self-employment taxes; the federal rate is 15.3%.

If you have people working for you, you’ll be responsible for sending tax forms to contractors or employees. People working for themselves can also manage their tax liability by carefully accounting for both their income and their expenses.

“Good records matter,” says Kimberly Key, a professor focused on accounting and taxation at Auburn University’s Harbert College of Business in Alabama. “2021 is going to help people figure out what they did wrong and try to get things fixed for 2022.”

Trading by individual investors, many using online platforms, reached historic highs during the early part of 2021, according to Nasdaq . Meanwhile, investments in cryptocurrencies such as Bitcoin reached all-time records last year.

If you didn’t sell any assets, Ellis says, you won’t have to pay taxes on them even if your portfolio did well.

If you bought and sold investments for the first time in 2021, you’ll soon get a crash course on capital gains taxes. You’ll have to gather records of your gains and losses. You’ll also want to distinguish between long-term capital gains (typically, for assets held longer than a year) and short-term capital gains (for assets held a year or less).

If you bought or sold stock, your brokerage will send you a tax form detailing your activity. Cryptocurrency exchanges, however, are not yet required to do so. In any case, it’s critical when filing your taxes to review any records sent by the investment platforms on which you’ve traded. If you don’t receive any records, you can log in to review your history.

Perhaps 2021’s most discouraging surprise was the persistence of COVID-19, which continued to sicken Americans throughout the year.

Even as vaccinations blunted some of the worst outcomes, many suffered from serious illness and significant medical costs. But if you spent more than 7.5% of your income on medical care, it may be possible to write off any expense beyond that threshold.

IF YOU HAVE KIDS

Anyone with kids — whether or not they joined your family in 2021 — will have to navigate the child tax credit, which saw a one-time expansion under the COVID-19 relief measures enacted early last year.

The federal government distributed payments from the child tax credit in advance based on income tax data from the 2020 tax year. Taxpayers were able to opt out, choosing to claim the deduction on their tax returns instead, but many did not.

The credit, with a maximum of $3,600 per child age 5 or younger at the end of 2021 and $3,000 for children ages 6 through 17, phases out at higher incomes. That means if you got a raise last year, you might no longer be eligible for the payment you received.

“I think the child tax credit this year is really going to throw a lot of people for a loop,” says Ellis, who runs The Bemused, a financial education program. “It was great when the checks were coming in, (but) some families will find that they need to repay part of that credit.”

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