What Is Alternative Minimum Tax?


The Alternative Minimum Tax (AMT) began as a way to keep wealthy taxpayers from using deductions to avoid paying income tax. The AMT’s purpose is to ensure everyone pays a minimum amount of tax. However, Congress hasn’t updated the factors that determine who must pay the AMT. As a result, more middle-income people must pay the AMT.

Exemption amount

Exemption amounts are set by law for each filing status. Since 2013, the exemption amounts have been adjusted each year for inflation. The exemption amounts for 2015 are:

  • $53,600 for single filers
  • $83,400 for married filing jointly and qualifying widow(er)
  • $41,700 for married filing separately

The AMT rate has increased substantially since its creation, but regular tax rates have decreased. So, instead of the AMT rate being much lower than regular tax rates, the regular tax rates are often lower than the AMT rate.

The AMT is a parallel tax system. You must:

  1. Complete your regular return.
  2. Complete AMT Form 6251.
  3. Compare the two taxes.
  4. Pay the higher of the two taxes.

You can’t claim many of the deductions you can claim for your regular tax computation for the AMT.

There’s no easy way to see if you’re subject to the AMT. However, you’ll usually be subject to it if you:

  • Have more than three children
  • Claim many deductions on your Schedule A
  • Exercise incentive stock options (ISOs) but don’t sell the stock in the same year

Personal exemptions

You’ll use Form 6251 to figure the AMT. It requires you to report adjustments to reflect the differences between the two parallel systems. So, you might have to add back amounts you deducted for regular tax purposes, like personal exemptions.

You must first calculate your AMT income:

  • If you itemize, start with your income after itemizing deductions. Don’t include your personal exemptions.
  • If you didn’t itemize, start with your adjusted gross income (AGI).

For AMT purposes, you can’t claim your personal exemptions. These exemptions reduce your income on your 2020 regular return by $4,300 per person. This amount is less for high-income individuals.

Also, if you itemize, you can’t claim as many deductions for the AMT as you can on your regular return. You must add them back into your income. The only itemized deductions allowed for AMT include:

  • Medical and dental expenses more than 10% of the regular tax AGI
  • Charitable donations
  • AMT investment interest to the extent of net AMT investment income
  • Qualified housing interest
  • Casualty losses
  • Miscellaneous deductions not subject to the 2% of AGI limitation

In the regular tax system, you can deduct most of your mortgage interest. How much you can deduct is subject to limitations based on the loan’s size. To learn more, see the Interest on Home Mortgage tax tip.

However, for AMT purposes, you might not be able to deduct the interest. This is true if you use mortgage money to do something on your first or second home other than:

  • Buy
  • Build
  • Substantially improve

This affects you if both of these are true:

  • You borrowed on a home equity loan or refinanced your mortgage for a loan that was more than the original debt.
  • You used some of the money for other purposes, like to buy a new car or pay down credit card debt.

AMT — Depreciation

The AMT has different depreciation rules than the regular tax system. Depreciation is often lower under the AMT. This is true especially for items you put into service before 1999.

You must figure a separate AMT depreciation for items put into service before 1999 if the items were for:

  • A business
  • Investment purposes

By doing this, you usually spread the depreciation over more years and at a less favorable rate.

This will also affect the amount of capital gain or loss you realize when you sell the depreciated asset. The basis of the property is equal to its cost adjusted up or down by certain amounts. This includes a downward adjustment for depreciation allowed.

If your depreciation is lower for AMT than for your regular taxes, your basis will be higher for AMT. Since you have a higher basis, your gain will be lower or your loss will be greater. This difference in basis usually results in an adjustment in the year you sell the asset. The adjustment will decrease the amount of income subject to AMT.

You must track AMT depreciation separately. This requires additional calculations to complete your return. Also, it’s a good idea to have good recordkeeping.

You usually must still figure depreciation for AMT purposes for these types of property:

  • Personal property that fits these requirements:
    • Placed in service after 1998
    • Depreciated using the 200% declining balance method

This is usually three-, five-, seven-, and 10-year property under the modified accelerated cost recovery system (MACRS). To learn more, see Form 6251 instructions.

  • Depreciation of real property that fits these requirements:
    • Placed in service after 1998
    • Not depreciated for regular tax purposes using the straight-line method
  • Most property placed in service after 1986 and before 1999

AMT — Incentive stock options (ISOs)

The ISO is a preference item. It’s often a major reason you have to pay AMT. To learn more about preference items, see Form 6251 instructions.

You might exercise an ISO but not sell the stock in the same year you exercised the options. If so, you don’t have income or loss to report on your regular return. It’s as though the transaction never happened. However, for AMT purposes, you must assume something did happen.

Usually, an ISO lets you buy stock at a price lower than the current fair market value (FMV) of a publicly traded stock. An income item for AMT purposes is the difference between these two items:

  • Amount paid for the stock — like your exercise price
  • Stock’s FMV on the day you exercised your option

AMT — Taxable tax-exempts

Income from municipal bonds usually isn’t taxable for regular tax purposes. However, you might have municipal bonds that are private-activity bonds. If so, you might have taxable income for AMT purposes. This is only true for private-activity bonds issued after Aug. 7, 1986. The Form 1099-INT you receive should show how much of your tax-exempt interest is subject to AMT. You might not have any.

AMT exemption

Your total AMT income and your filing status determine your exemption amount. Exemption amounts for 2020 are:

  • Married filing jointly or qualified widow(er) — $83,400
  • Single or head of household — $53,600
  • Married filing separately — $41,700

For 2020, the exemption amounts are phased out at the rate of 25 cents for each $1 of AMT income more than:

  • Married filing jointly or qualified widow(er) — $158,900
  • Single or head of household — $119,200
  • Married filing separately — $79,450

You’ll have income subject to the AMT after you subtract the exemption amount from the AMT income. The AMT rate is a flat 26% for income up to $92,700 — or $185,400 if married filing jointly. Income more than those amounts is taxed at a rate of 28%. Income taxed at a lower rate — like long-term capital gains or qualified dividends — is still subject to those rates, not the AMT rate.

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