The IRS provides a wealth of preliminary tax data for tax year 2015 in the Spring 2017 Statistics of Income Bulletin (SOIB). The data is based on a sample of 257,083 individual income tax returns for 2015, processed between January and late September of 2016, out of a total of 150.6 million returns. The preliminary data can be found at https://www.irs.gov/pub/irs-soi/soi-a-inpd-id1703.pdf.
Included in the SOIB is data on itemized deductions. Based on the IRS sample, the standard deduction was claimed on 69.2% of 2015 returns and itemized deductions were claimed on only 29.5%(neither the standard deduction nor itemized deductions were needed on the remaining 1.3% of returns that had no AGI). The amount of total itemized deductions claimed increased 4.2% compared to 2014, up to $1.2 trillion. The average claim for itemized deductions was $27,053.
The most claimed itemized deduction by far is the deduction for taxes paid, which includes state and local income taxes and general sales taxes as well as real estate taxes. For 2015, $539.8 billion in taxes was deducted, 6.2% more than for 2014. The next largest deduction, for interest paid, was down 1%, to $294.5 billion, of which 94.6%, or $278.5 billion, was for mortgage interest. Charitable contribution deductions totaled $201.3 billion, a 6% increase. Medical and dental expenses were up 3.5% to $84.2 billion.
Based on the IRS data, we have prepared the table below, which shows the average 2015 itemized deductions claimed for medical (including dental) expenses, taxes, interest, and charitable contributions by taxpayers in the seven AGI categories provided by the IRS. Note that the highest income group is for those with AGI of $250,000 or more. The averages shown for these taxpayers may be misleadingly high, because the amounts claimed by the very highest earners could dwarf those claimed by those with AGI closer to $250,000, but the IRS does not provide a further break-down.
AVERAGE ITEMIZED DEDUCTIONS FOR 2015
|Under $15||$ 9,210||3,667||6,397||1,533|
|250 and more||37,032||51,906||16,580||21,769|