Here's the reason you need to check your pay stub

  • The IRS wants you to make sure you're withholding the right amount of tax from your pay.
  • New tax law lowers individual income tax rates by 1 percent to 3 percent.
  • Incorrect withholding could place you on the hook for a big tax bill in 2019.
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When pay day rolls around, be sure to take a close look at your pay stub. This could make the difference between owing the Internal Revenue Service in 2019 or snagging a refund.

The IRS kicked off its "Check Your Paycheck" campaign on Monday, asking taxpayers to take a peek at their pay stubs and ensure that they're withholding the right amount from their pay.

It's a good practice to review the amount of taxes withheld from your pay, but it's especially important this year in light of the Tax Cuts and Jobs Act.

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The new law slashed individual income tax rates by 1 percent to 3 percent, doubled standard deductions and eliminated personal exemptions.

The tax overhaul has also led the IRS to change its income tax withholding tables, which employers and payroll companies use as guidance on how much they ought to deduct from workers' pay.

To help you better determine how much income tax you ought to withhold from your wages, the IRS launched a new withholding calculator and a new Form W-4.

Here's how you can ensure that you're paying the right amount of taxes in 2018.

Tailor your taxes

You likely began seeing changes to your paycheck in February.

Your Form W-4 determines the amount of income tax withheld from your pay based on a number of criteria, including whether your spouse works, whether you have children and whether you itemize.

If you withhold too much, you'll get a refund the following year. Fail to withhold an adequate amount, and you'll owe the taxman (and possibly penalties).

Withhold correctly

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If you're an employee, your employer gave you a Form W-4 when you were hired, which you can adjust to make sure the right amount of income tax is withheld from your paycheck.

On the form, you'll make note of your spouse, your dependents and your filing status; these are your "personal allowances." The more allowances you have, the less tax will be withheld.

"Some people read the form and think, 'I'm married and have three kids,'" said Cari Weston, director of tax practice and ethics at the American Institute of CPAs. "They end up with five allowances and owe substantial taxes at the end of the year."

Avoid underpayment

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You can use your 2017 tax return to get some idea of how much you ought to withhold this year.

To ensure that you avoid a penalty for underpayment of estimated taxes, you should aim to pay in 2018 at least 100 percent of the prior year's liability, said Jeffrey Levine, CEO and director of financial planning at BluePrint Wealth Alliance in Garden City, New York.

This doesn't mean that you won't owe in April 2019. Rather, it means the IRS won't charge you the penalty and interest next year for coming up short on your taxes.

"If you see your tax rate increase substantially, you might owe a larger amount over the withholding," said Levine. "Aim for that 100 percent: It's a better method of avoiding the underpayment penalty."

Pinpoint your tax load

Here are some suggestions to help you nail the right amount to withhold.

  • Review your W-4: Finding a balance for your withholding is based on your salary, your spouse's earnings and the tax bracket you're in.

    We're in a year with many changes to the withholding table, plus a reduction in federal income tax rates. You may be taking home a slightly larger paycheck, but you should make sure you aren't withholding too few taxes.

  • Talk to your accountant: If you withheld fewer taxes in previous years because you itemized deductions on your return, then it's time for another look at your W-4.

    That's because the new law does away with a lot of itemized deductionsand places a $10,000 cap on state and local tax deductions.

  • Don't play with tax arbitrage: If you withhold less in taxes because you have bigger plans with your paycheck, bear in mind that you'll owe Uncle Sam next year. Don't gamble your cash.

    "Some people do foolish things: 'If I invest the money and make 7 percent this year, and I beat the IRS penalty, then I'm ahead,'" said Levine. "If you've deliberately underpaid, the money should go someplace safe because this is a really short-time horizon," he said.