• Limitation on itemized deductions — Once adjusted gross income (AGI) exceeds $78,200 in 2007 for married couples filing separately and $156,400 for all other taxpayers, itemized deductions, with the exception of medical expenses, investment interest, and casualty losses, must be reduced by 3% of the excess over this AGI amount. The maximum reduction is 80% of itemized deductions. In addition, medical expenses can only be deducted to the extent they exceed 7.5% of AGI, while miscellaneous expenses must exceed 2% of AGI and casualty losses must exceed 10% of AGI.

• Phase out of personal exemptions — The personal exemption amount of $3,400 in 2007 is reduced by two-thirds of 2% of each $2,500 of AGI over threshold amounts. Those amounts for 2007 are $234,600 for married taxpayers filing jointly, $195,500 for heads of household, $156,400 for single taxpayers, and $117,300 for married taxpayers filing separately.

• Exclusion of Social Security benefits from income tax — Up to 50% of benefits are taxed when AGI plus tax-free interest plus one-half of Social Security benefits is over $25,000 but less than $34,000 for single taxpayers and is over $32,000 but less than $44,000 for married couples filing jointly. Up to 85% of benefits is taxed once income exceeds $34,000 for single taxpayers and $44,000 for married couples filing jointly.

• Other phase outs — Numerous credits, deductions, and other benefits are phased out once income exceeds prescribed limits, including the earned income credit, the child credit, the dependent care credit, traditional and Roth individual retirement account (IRA) contributions, Coverdell education savings account contributions, Hope scholarship and lifetime learning credits, the above-the-line higher education expense deduction, student loan interest deductions, rental real estate losses under passive loss rules, the adoption credit, and the elderly and disabled credit.

While these items are not called income taxes, the result is the same — an increase in your total income tax bill.