The IRS gives taxpayers a couple of months of lead time every year in telling taxpayers what the tax brackets will be for the coming year. Last year, there was a lot of uncertainty about whether the pre-released 2017 tax brackets would actually be the ones taxpayers would end up using, but tax reform has taken longer than some had expected.

Many Americans are more hopeful about the prospects for tax changes taking effect in 2018, but that hasn't stopped the IRS from releasing 2018 tax brackets. Below, you can see what will be in place if tax reform doesn't happen in the coming year.

Keyboard with blue tax key.

Image source: Getty Images.

2018 tax brackets for singles

If you're not married and don't qualify for the tax breaks that filing as a head of household or a qualifying widow or widower offer, then the brackets that apply are:

Bracket

Tax Is This Amount Plus This Percentage...

...of the Amount Over

$0 to $9,525

$0 plus 10%

$0

$9,525 to $38,700

$952.50 plus 15%

$9,525

$38,700 to $93,700

$5,328.75 plus 25%

$38,700

$93,700 to $195,450

$19,078.75 plus 28%

$93,700

$195,450 to $424,950

$47,568.75 plus 33%

$195,450

$424,950 to $426,700

$123,303.75 plus 35%

$424,950

above $426,700

$123,916.25 plus 39.6%

$426,700

Data source: IRS.

2018 tax brackets for heads of household

Those who are not married and support a child, parent, or other relative who lives with you more than half the year and meets certain other qualifications can file as head of household. It's often necessary for you to claim qualifying persons as dependents. Heads of household get wider brackets that result in lower taxes.

Bracket

Tax Is This Amount Plus This Percentage...

...of the Amount Over

$0 to $13,600

$0 plus 10%

$0

$13,600 to $51,850

$1,360 plus 15%

$13,600

$51,850 to $133,850

$7,097.50 plus 25%

$51,850

$133,850 to $216,700

$27,597.50 plus 28%

$133,850

$216,700 to $424,950

$50,795.50 plus 33%

$216,700

$424,950 to $453,350

$119,518 plus 35%

$424,950

above $453,350

$129,458 plus 39.6%

$453,350

Data source: IRS.

2018 tax brackets for married joint filers

Most married taxpayers file jointly, and the same tax brackets also apply to qualifying widows and widowers.

Bracket

Tax Is This Amount Plus This Percentage...

...of the Amount Over

$0 to $19,050

$0 plus 10%

$0

$19,050 to $77,400

$1,905 plus 15%

$19,050

$77,400 to $156,150

$10,657.50 plus 25%

$77,400

$156,150 to $237,950

$30,345 plus 28%

$156,150

$237,950 to $424,950

$53,249 plus 33%

$237,950

$424,950 to $480,050

$114,959 plus 35%

$424,950

above $480,050

$134,244 plus 39.6%

$480,050

Data source: IRS.

2018 tax brackets for married separate filers

If you're married and file separately, different brackets apply. As you can see, the brackets are divided equally in half compared to joint filers.

Bracket

Tax Is This Amount Plus This Percentage...

...of the Amount Over

$0 to $9,525

$0 plus 10%

$0

$9,525 to $38,700

$952.50 plus 15%

$9,525

$38,700 to $78,075

$5,328.25 plus 25%

$38,700

$78,075 to $118,975

$15,172.50 plus 28%

$78,075

$118,975 to $212,475

$26,624.50 plus 33%

$118,975

$212,475 to $240,025

$57,479.50 plus 35%

$212,475

above $240,025

$67,122 plus 39.6%

$240,025

Data source: IRS.

Other key information about your tax bracket

A lot of taxpayers find tax brackets bewildering. For instance, if you're in the 25% bracket, you won't pay a 25% tax rate on all of your income. For instance, single filers with taxable income of $40,000 are in the 25% bracket, but only the final $1,300 in income you earned actually gets taxed at that rate. The rest gets more favorable 10% or 15% tax rates.

In addition, tax brackets use taxable income as their starting point. This reflects reductions from personal exemptions and either the standard deduction, or itemized deductions. It can therefore be much lower than your gross income.

Finally but most importantly, these brackets are subject to change. If tax reform goes forward, these brackets could become history. However, if implementation of any future tax changes doesn't take effect until the 2019 tax year, you'll use these brackets.

To plan for your taxes, information about your tax bracket is useful. Knowing what you would have paid under the old tax laws will tell you how much you win or lose from any tax reform package that becomes law.