IRS Provides Historical Tax Return Statistics

2011 Corporation Tax Returns Line Item Estimates 

The Corporation Income Tax Returns Line Item Estimates publication presenting estimates of frequencies of taxpayer entries recorded on the applicable lines of the forms and schedules filed with corporation tax returns as shown in the 2011 Statistics of Income (SOI) Complete Report (Publication 16) is now available. This publication also contains the corresponding population estimates of dollar amounts recorded on those lines (as applicable). The first year of availability for this data was 2008. 

2012 Individual Income Tax Returns Percentiles Data 

Tax Year 2001-2012 individual income tax return statistics by selected descending and ascending cumulative percentiles are now available. These updated tables show historical statistics from 2001 through 2012 on income and tax by cumulative percentiles based on numbers of returns. The tables show distributions of adjusted gross income (AGI) and total income tax, as defined for each tax year, by descending and ascending cumulative percentiles of returns in both current and constant dollars. They can be used to make comparisons across cumulative percentile classes beginning with Tax Year 2001. This release is based on all individual income tax returns except returns of dependents.

Sources: Internal Revenue Service at http://www.irs.gov/uac/Tax-Stats-2