Many taxpayers must calculate their federal income tax liability under two sets of rules: those applying to the regular income tax and those of the alternative minimum tax. If a taxpayer owes more tax under the alternative rules, then the difference is paid as AMT. The AMT hits people in some states harder than it does in others because state and local income and property taxes are not allowed as itemized deductions against the AMT and because income varies across states. This column discusses AMT participation rates by state.