Return to the main Income from Trusts and Estates Study Metadata page This page contains information about data sources and limitations for SOI's Income from Trusts and Estates Study. Please visit Income from Trusts and Estates Statistics to access articles and tables from the study. The data presented here were collected from returns processed for administrative purposes and is organized by filing year. A filing year includes returns submitted to the IRS for processing between January 1 and December 31 of that year. A filing year is primarily comprised of returns for the tax year immediately prior. However, a filing year may include returns from numerous other tax years. For example, Filing Year 2008 includes more than 2.8 million returns for Tax Year 2007; 93.25 percent of the population for that year. About 1.95 percent of the Filing Year 2008 population is for Tax Year 2006. Filers of Form 1041 do not represent the universe of all trusts, particularly grantor trusts. Optional filing methods allow grantor trusts with a single grantor to report trust income through the U.S. Individual Income Tax Return (Form 1040) of the grantor. All amounts were recorded prior to any audit or taxpayer correction subsequent to the original filed return, with the exception of tax liability. Tax liability amounts noted in this article are “settlement amounts,” which include any changes made during processing or audit procedures. Therefore, these amounts may differ from the tax liability reported by the taxpayer on Form 1041.The data were extracted from the Internal Revenue Service (IRS) Returns Transaction File (RTF). Amended returns filed for the prior tax year were removed from the populations for the purposes of this study. The data presented in this article have been tabulated using these adjusted populations of Form 1041. Fiduciary income tax returns are processed according to the guidelines presented in the Internal Revenue Manual for Returns and Documents Analysis for Income Tax Returns for Estate and Trusts. The resulting data is recorded on the RTF. Tests were run on the data to check for and correct non-sampling errors. Common types of errors found in the processing data included keying errors and incorrect mathematical calculations.