The Pease limitation, which restricts the amount of itemized deductions a taxpayer can claim, has been around for more than two decades; after briefly being phased out and repealed at the end of last decade, it has returned in full force for 2013 as a result of the American Taxpayer Relief Act of 2012. The reinstatement of the Pease limitation applies with the same rules that existed previously - phasing out itemized deductions by 3% of every dollar over the threshold - though the new rules did increase to the threshold to a new, higher amount.
Given how the Pease limitation is calculated though - as a percentage of income above the threshold, and not directly based on deductions - the reality is that the Pease limitation should actually more properly be viewed as a surtax on income, not a limitation on deductions. Although the amount of deductions does matter in certain limited circumstances - particularly with ultra-high-income taxpayers living in states with no state income taxes - for most, the Pease limitation simply lifts the top 3 tax brackets by about 1% - 1.2% without directly impacting the benefits of tax deductions at all!
This distinction of whether the Pease limitation is driven primarily by income or by deductions is important, as it affects the relative value of various income and deduction strategies. In fact, while the common conclusion from the media and some political pundits has been that the Pease limitation is a disincentive to tax deduction strategies like charitable giving, the reality is actually that there are only a few limited circumstances where the benefits of charitable giving may be diminished indirectly by the Pease limitation, and in the end the overwhelming majority of individuals who face the Pease limitation will actually still enjoy the full tax benefits of their charitable giving strategies!