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Calculating Your Taxes

Navigating your 1040

Our Two Cents

File on time! You can get an extension—but you will be charged interest on any amount that is not paid by April 15. There’s also a penalty for late filing.

Anyone with income over a certain amount must pay federal income taxes. Most states also impose an income tax, and in some places there are local income taxes as well. As we discussed in Income Taxes, tax rates vary by the amount of income and whether you're a single filer or married filing jointly.

Calculating your taxes and filing your income tax return can sometimes be confusing. This page is intended to help you understand and complete your individual tax return using IRS Form 1040. If your situation is complex, you may want to consult with a tax advisor.

What is total or gross Income? [Line 22]

Your total or gross income includes:

  • Earned income, which comes from employment and can take the form of wages, salary, tips, commissions and bonuses. Earned income may be subject to both income and payroll taxes.
  • Unearned income, which comes from sources other than employment, such as dividends, interest, capital gains or U.S. savings bonds. Most unearned income is subject to income taxes.

Important things to remember

  • Other sources of taxable income include alimony, unemployment compensation, gambling winnings or lottery winnings.
  • Income that's not taxable (these are called exclusions) include: a gift or inheritance, child support, life insurance proceeds following the death of the insured, interest from municipal bonds (may be subject to federal alternative minimum tax, plus state tax for out-of-state bonds), disability income if you paid the premium with after-tax dollars, and certain employee fringe benefits.
  • If you have stocks, bonds or other investment assets in a taxable account your profit or loss is known as a capital gain or a capital loss. Capital gains are currently taxed at a maximum rate of 20 percent, but only for people in the highest tax brackets. Otherwise, long-term capital gains are taxed at 15% or 0%, depending on your marginal tax bracket.

Filing Tip for Parents:

If you’re a parent, your child’s taxable income is inherently linked to yours. Get information for filing for a dependent and learn about the kiddie tax

How to calculate your adjusted gross income [Line 37]

Your adjusted gross income (AGI) is an important part of your tax calculation. To get your AGI, you can subtract certain deductions from your income to reduce the amount of income that will be taxed.

Some examples of deductions that help determine your AGI:

  • Deductible IRA contributions
  • Contributions to a Keogh (self-employed) retirement plan
  • Self-employed health insurance deductions
  • One-half of self-employment tax
  • Alimony paid
  • Qualified moving expenses
  • Penalty on early withdrawal of savings
  • Qualified higher education expenses
  • Teacher's education expenses up to $250
  • Qualified education interest

Why your AGI is important

Your AGI also determines your eligibility for certain other deductions and credits. For example, you are eligible to contribute to a Roth IRA only if your AGI is under $114,000 for single filers and under $191,000 if you're married filing jointly.

Choosing standard or itemized deductions [Line 40]

Once you know your AGI, you have the opportunity to lower your taxable income even more by subtracting either the standard deduction or your itemized deductions—whichever is greater.

When to consider the standard deduction

If your financial situation is straightforward, the standard deduction might be the best and simplest choice. The standard deduction for 2014 is $6,200 for single filers, $12,400 for married filing jointly and $9,100 for head of household.

When to consider itemizing deductions

If you pay a lot in state income taxes, have a mortgage on your home, give a lot to charity, have paid extensive medical bills or manage a lot of investments, you might be better off taking the extra time to itemize your deductions.

Examples of legitimate itemized deductions:

  • Property taxes
  • State and local income taxes (or state sales taxes if your state does not have an income tax)
  • Specified medical and dental expenses that exceed 10 percent of your AGI (or 7.5 percent if you are 65 or older), including limited amount of premiums paid for long-term care policies
  • Mortgage interest on first and secondary residences (up to maximum debt of $1 million), plus interest on home equity loans (maximum debt up to $100,000)
  • Charitable contributions to tax-exempt organizations
  • Casualty and theft losses (see IRS guideline)
  • Investment interest expense (e.g., margin interest expense)
  • Miscellaneous expenses, including impairment-related expenses for persons with disabilities and gambling losses to the extent of gambling winnings
  • In addition, the following can be itemized if the cumulative total is more than 2 percent of your AGI:
    • Business expenses not paid by your employer (such as union or professional dues, unreimbursed travel or uniforms)
    • Tax-preparation fees
    • Investment advisor fees

What you CAN'T deduct

Keep in mind that you can’t deduct political contributions, credit card interest or interest on a personal car loan.

How many personal exemptions you can claim? [Line 6d]

A personal exemption is an amount you can subtract from your AGI that is determined by the government and indexed annually for inflation. For 2014, the personal exemption is $3,950.

You can claim three kinds of personal exemptions:

  • For yourself—You're allowed one exemption for yourself.
  • For your spouse—If you're married and filing a joint return, you’re allowed two exemptions: one for yourself and one for your spouse.
  • For your dependents—You're allowed an exemption for each qualified dependent, which can be a child or other relative.

What’s a qualified dependent?

A child is qualified based on age, relationship to you, residency and means of support. Another relative can be qualified based on the relationship to you, the relative’s gross income and the amount of support that you supply. For more details, go to

Determining taxable income [Line 43]

Once you know your AGI and the deductions and exemptions you qualify for, you can calculate your taxable income and your tax due. On the IRS website, you’ll find tips on taxable and nontaxable income as well as detailed tax tables (PDF)

What's your tax rate?

You pay a proportionately larger amount of taxes on higher amounts of income. This results in two different tax rates:

  • Your marginal tax rate is the percentage of tax you pay on your last dollar of taxable income.
  • Your average tax rate is just that—the average amount that you pay taking into consideration all of your income.

For example, if you are single and your taxable income is $40,000, your marginal income tax rate is 25 percent, but your average tax rate is likely quite a bit lower.

Your combined tax rate and your investment return

There's one more tax rate you need to consider: your combined marginal tax rate. This includes your state income tax rate plus your federal income tax rate. So, if you pay 25 percent in federal taxes and 5 percent in state taxes, your combined rate is 30 percent. This number is especially important when calculating your return on an investment. Because if an investment earns 8 percent and your combined marginal tax rate is 25 percent, your rate of return is really 6 percent.

Making use of tax credits [Lines 47–54]

A tax credit reduces the taxes you owe dollar for dollar. A credit is more valuable than a deduction. A $100 credit means that you pay $100 less in taxes. A deduction simply reduces your taxable income.

There are a number of tax credits available, depending on your income and personal situation. A few examples include:

  • Credit for qualified adoption expenses
  • Credit for a qualified child under the age of 17
  • Child and dependent care credit
  • Residential energy credit
  • American Opportunity education tax credit (formerly the Hope credit) for qualified expenses during the first four years of college.
  • Lifetime learning credit for expenses related to improving job skills and for pursuing an undergraduate, graduate or professional degree. Learn more at

A frequently overlooked credit

Some low-income working individuals and families will qualify for the Earned Income Tax Credit. This valuable benefit provides an actual refund, not just a credit against taxes due. You can find out if you qualify by visiting

How to arrive at your tax due [Line 63]

After you've figured out your taxable income, there are a few more steps to arriving at your actual tax due.

  • Subtract any payments and/or credits from your taxes owed. [Line 74]
  • On lines 75 and 76, you will determine whether you owe taxes or will receive a refund.

If you're getting a big refund, you're probably having too much withheld from your paycheck. In effect, this means you're giving the government an interest-free loan. On the other hand, if you have too little withheld, you may be charged an underpayment penalty.

Payroll taxes 101.

Who pays FICA and Medicare taxes?

  • An additional 12.4 percent of your income (up to $117,000 in 2014) will be paid into Social Security, and 2.9 percent (with no limit) will be paid to Medicare on your behalf.

If you're a wage or salaried employee, your employer will pick up half of this tab (so you'll pay 6.2 percent into Social Security and 1.45 percent into Medicare). This means that a total of 7.65 percent of your paycheck will be withheld, and your employer will also pay 7.65 percent.

What if you're self-employed?

If you're self-employed, you pay the entire 15.3 percent of FICA and Medicare taxes. In this case, you can deduct half of this tax from your gross income when calculating your AGI.

What records to keep

Doing your taxes will be a lot easier if you keep the right records—and keep them easily accessible. It’s wise to keep:

  • All of your tax returns for seven years. This includes all supporting documents such as forms that show your income and validate your deductions: W-2, 1099s, canceled checks, receipts for charitable contributions, etc.
  • All home ownership documents, including records of home improvements. (You'll need this to calculate your tax basis when you sell your home.)
  • Investment records, including what you paid and when you sold.
  • Statements for retirement accounts. In particular, you will need to have records of after-tax contributions.

A word about tax audits

Even though the IRS only has three years to audit your return, they have six years to follow up if you underreport your income by more than 25 percent. Also, if you don’t file a return or file a fraudulent return, there are no time limits on when they can investigate.


The information on this website is for educational purposes only. It is not intended to be a substitute for specific individualized tax, legal, or investment planning advice. Where specific advice is necessary or appropriate, consult with a qualified tax advisor, CPA, financial planner, or investment manager.

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