Gross Income: your total income before any taxes or deductions whatsoever. For most people, this is not their "take-home" income since money is deducted automatically by employers. If you are filing jointly with your spouse, enter your total combined gross income.
Filing Status: the options are Single, Married Filing Jointly, Married Filing Separately, Head of Household, or Qualifying Widow(er). Obviously, you want to select the filing status that will save you the most money--just make sure you're eligible for it. You can use the calculator to see which filing status saves you the most money.
Dependents: the number of dependents you will claim. Dependents are most commonly children or elderly retired family members living with you. However, the definition of "dependent" is potentially broader to include other people who get most of their living expenses paid by you. You should consult the IRS's definition of "dependent" if your dependent is not a child or elderly retired family member living with you, to make sure you qualify. Remember that dependents cannot claim themselves on their own income taxes (they cannot receive the standard deduction).
Itemized deductions: the total amount of all income you are claiming as itemized deductions (not counting standard deductions for yourself and dependents). The calculator requires you to have itemized deductions calculated already. It will not calculate them for you. Deductions that can be itemized include charitable contributions, certain medical expenses, and home mortgage interest, among many other categories. There are specific rules for what qualifies for a deduction (not all houses' mortgage interest is deductible, for instance). Given how complex itemizing deductions can get, you should strongly consider going to an accountant or at least a tax preparer.
The Effective Tax Rate Concept Explained
What percentage of your income do you pay in federal personal income tax? The answer is not as straightforward as it might seem. The United States, like just about every other major economy, does not use a flat income tax. Instead, the US uses a progressive income tax. Your income tax rate progresses (increases) the more you make.
Your federal income tax rate does not increase with every extra dollar you earn. Your income has to pass a certain threshold for your rate to increase. The spaces between the thresholds are called income brackets or tax brackets.
Federal Income Tax Bracket Table
The thresholds for the 2005 tax year stand at:
- Up to $7300: 10% tax rate
- $7300 - $29,700: 15% tax rate
- $29,700 - $71,950: 25% tax rate
- $71,950 - $150,150: 28% tax rate
- $150,150 - $326,450: 35% tax rate
How Tax Brackets Work
You pay the tax rate for each tax bracket for the part of your income in that bracket. So if you earned $100,000 of taxable income, you would not pay 28% of your income. Instead, you would pay 10% on the part under $7300, 15% on the part between $7300 and $29,700, 25% on the part between $29,700 and $71,950 and 28% on the part between $71, 950 and $100,000.
Marginal Tax Rate
As you can see, your highest tax bracket is important for you to keep in mind, even though only a small part of your income falls into it. That's because any additional income you make above and beyond what you're making already will be taxed at that highest bracket's rate. The highest bracket's rate is so important that it has its own name: the marginal tax rate.
The marginal tax rate is especially important when you are coming into a windfall of money. The most common case when the marginal tax rate is important is when you are cashing out investments. The worst case scenario is that your windfall will push you into a higher bracket. In that case, you might want to consider only taking part of your windfall this tax year. For instance, you could sell half your stock now and half next year. Or, you could pursue getting more tax deductions. If you'd always wanted to make a charitable contribution, this scenario might be a good time to do so.
Gross Income and Taxable Income
The entire amount of money you earn in a year is called your gross income. Your taxes are not based on your gross income. Instead, they're based on your taxable income. Your taxable income is your income minus any tax deductions.
Everyone has some tax deductions. The obvious deductions are for Social Security and Medicare. These amounts are generally taken out of your pay automatically. The government then calculates your taxes based on what's left over, not on your total earned income. You similarly get an automatic deduction for state income tax. If 5% of your income goes to paying state income tax, the amount lost to state tax won't be double-taxed by the federal government (note: this may change for the 2006 tax year, as there are proposals in Congress to eliminate the state tax deduction).
There are also tax deductions for having children, making contributions to nonprofits, and many other kinds of expenses. If you have many different tax deductions, you may choose to itemize. When you itemize your tax return, you cannot use the simple EZ forms for filing taxes. If you're itemizing your taxes, it's widely considered a very good idea to go to an accountant or at least a professional tax preparer. If you want to itemize and you absolutely refuse to get professional tax help, at least use a software program that will help you figure out the itemization.
Calculating an Effective Tax Rate
The hodgepodge of tax brackets and deductions means that everyone pays a slightly different percentage of their income as income tax. But sometimes, you need to know just how much of your income goes toward the federal income tax. For instance, many formulas for personal budgeting ask for the percentage of your income that goes to federal income tax.
The actual percentage of your total income that goes to federal income tax is called the "effective tax rate." To figure out your effective tax rate, you first need to figure out your taxable income by subtracting any deductions from your total income. You then need to divvy up your income into the different tax brackets. Then add up the tax due from each bracket of income. Or you can use the effective tax rate calculator.