SOI Tax Stats - Exempt Organizations Unrelated Business Income (UBI) Tax study data sources and limitations

This page contains information about data sources and limitations for SOI's Exempt Organizations' Unrelated Business Income (UBI) Tax study.

Please visit the Exempt Organizations' Unrelated Business Income (UBI) Tax to access the annual data tables and articles from the study.

The unrelated business income statistics of nonprofit charitable and other tax-exempt organizations produced by the Statistics of Income (SOI) Division are based on a sample of Forms 990-T, Exempt Organizations Unrelated Business Income Tax, filed with the Internal Revenue Service for a specified tax year. In order to qualify for the sample, a tax exempt organization must earn the filing threshold of $1,000 or more from regularly conducted business activity that is not substantially related to its exempt purpose.

The SOI Form 990-T study incorporates a two-stage sample design consisting of a stratified random sample and a special "integrated" sample. The stratified random sample is designed to represent the entire population of Form 990-T filers reporting unrelated business income. The integrated sample is designed to gather information on "related" (tax-exempt) and "unrelated" (taxable) income and expenses for section 501(c)(3) nonprofit charitable organizations that filed both Form 990 (or Form 990-EZ) and Form 990-T. This sampling program ensures that the SOI sample of Forms 990-T includes any qualifying unrelated business income tax returns filed by organizations whose Form 990 or Form 990-EZ information returns were selected for the separate SOI sample of section 501(c)(3) nonprofit charitable organizations. Organizations exempt under other Code sections were not subjected to the integrated sampling program. The designed sampling rates ranged from a minimum of 3.65 to a maximum of 100 percent. 

For a given tax year, SOI's population estimates differ slightly from the actual population of Form 990-T returns that post to the IRS Business Master File during the two-year sampling period. This results from sample code changes and the effects of returns that are “rejected” from the sample as part of the editing process. Examples of returns present on the Master File but rejected from the SOI sample include: those that had gross unrelated business income below the $1,000 filing threshold; were filed for a part-year accounting period, and a full-year return was also filed; were filed for a part-year accounting period that began in a year other than the given tax year; and duplicate filings by a single organization.

The data presented are obtained from returns as originally filed with IRS. In most cases, changes made to the original return because of administrative processing or audit procedures are not captured in the statistics. Changes made based on taxpayer amendment are captured, if available. The data are subjected to comprehensive testing and correction procedures in order to ensure statistical reliability and validity. A general discussion of the reliability of estimates based on samples, methods for evaluating both the magnitude of sampling and non-sampling error, and the precision of sample estimates can be found in the general Appendix of the most recent SOI Bulletin.