Even if you’ve worked to get your taxes just right in previous years, changes in the tax law could mean big changes in what you owe. That may hold true even if your job and personal situation haven’t changed. That could mean a surprise tax bill. Here’s what to look out for.

Did You Update Your Withholding This Year?

After the new tax law passed, the IRS created new W-4s and withholding tables. They said you don’t need to fill out a new one, but there’s a good chance your old one may not be accurate.

Even though your employer should automatically adjust your withholding rate based on your number of dependents, things could be off if you previously changed your number of exemptions. The biggest thing that may lead to a possible surprise tax bill is if you previously manually increased your exemptions because you kept getting a large refund under the old law. The new tables may more accurately reflect your situation without those adjustments, or you may have lost deductions.

Are You in an Income Tax State or Do You Have High Property Taxes?

Beginning in 2018, the maximum combined deduction for state income taxes and property taxes is $10,000. If your state taxes are higher than that, you’ll likely see an increase in your federal tax bill since your total itemized deductions won’t be as high as they were in the past.

Do You Have Multiple Dependents?

Under the new law, there are no more personal exemptions. Instead, there’s either a $12,000 or $24,000 standard deduction based on whether you file single or married. This amount does not change if you have children.

In place of the old exemptions is a new Child Tax Credit. Several other tax credits and deductions, such as for childcare, healthcare, and educational expenses, were also reworked. Congress intended for the changes to offset each other. However, some families may see higher or lower bills based on exactly what they claimed in the past.

Note: If you’re divorced with children and could claim the exemption in your divorce agreement, you’ll need to talk to your divorce attorney. You may need to update your agreement to take the new law into account.

Avoid a Surprise Tax Bill

There were several big changes in the tax law that could lead to you pay more in taxes than you did last year. The changes above will affect the most people, but there could be less common changes that apply to you. Be sure to review your tax situation with your accountant. That’s one crucial way to avoid a surprise tax bill at the end of the year.