SOI Microdata

The IRS’s Statistics of Income (SOI) Division provides statistics collected from income tax and information returns to government agencies and the general public.

To accomplish this, it creates a yearly representative sample of data from the nonprofit sector (found in microdata files here) and uses it to produce reports and statistics:

https://www.irs.gov/statistics/soi-tax-stats-charities-and-other-tax-exempt-organizations-statistics

"The samples include Internal Revenue Code section 501(c)(3) organizations and section 501(c)(4)–(9) organizations. Sampling rates ranged from 1 percent for small-asset classes to 100 percent for large-asset classes. Microdata records contain information on balance sheets and income statements, as well as weights (to estimate the population), for each organization."

Sampling framework:

https://www.irs.gov/statistics/soi-tax-stats-exempt-organizations-study-data-sources-and-limitations

The SOI Division’s statistics about nonprofit charitable and other tax-exempt organizations are based on a sample of Forms 990 (Return of Organization Exempt From Income Tax) and Forms 990-EZ (Short Form Return of Organization Exempt From Income Tax), which are tax documents the organizations submit to the IRS for a specific tax year. The sample does not include private foundations (Form 990-PF filers) and most churches and certain other types of religious organizations that don’t file Form 990 or Form 990-EZ.

Recent samples include only those returns with average receipts of more than $25,000, the current filing threshold. Starting in tax year 1988, the sample design is split into two parts: the first part includes returns filed by organizations exempt under Internal Revenue Code (IRC) section 501(c)(3), while the second part comprises returns filed by organizations exempt under IRC sections 501(c)(4) through (9).

Organizations that are tax-exempt under other IRC sections are not part of the sample frames. The two samples are organized into strata based on the total assets these organizations have at the end of the year, and each stratum is sampled at different rates.

The sample of exempt organizations is designed to provide reliable estimates of their total assets and total revenue. To accomplish this, all returns filed for section 501(c)(3) organizations with total assets of $50 million or more are included in the sample, since these organizations represent the vast majority of financial activity. All of the section 501(c)(4)-(9) organizations with assets of $10 million or more are included in the sample.

The rest of the organizations are randomly selected for the sample at varying rates, ranging from about 1 percent to less than 100 percent, depending on their asset size. (For a historical list of exempt organization study sample and population counts, see the table at the end of this section.)

For a given tax year, the SOI Division's population estimates differ slightly from the actual population of Forms 990 and 990-EZ returns that are recorded in the IRS Business Master File during the two-year sampling period. This results from sample code changes and returns that are “rejected” from the sample during the editing process.

Returns that are present in the Master file but omitted from the SOI sample include the following:

• certain returns that report an incorrect subsection code • returns that are filed for an incorrect tax year • duplicate filings by a single organization

The data presented are obtained from the initial returns filed with the IRS. In most cases, changes made to the original return because of administrative processing or audit procedures are not captured in the statistics. However, changes made by taxpayer amendment are captured, if available.

Data undergo comprehensive testing and correction procedures to ensure statistical reliability and validity. For a general discussion of the reliability of estimates based on samples, methods for evaluating both the magnitude of sampling and nonsampling error, and the precision of sample estimates, you can refer to the general appendix of the most recent SOI Bulletin.

• [2013]
• [2014]
• [2015]
• [2016]
• [2017]
• [2018]
• [2019]

Microdata files in ASCII format:

https://www.irs.gov/statistics/soi-tax-stats-charities-and-other-tax-exempt-organizations-statistics

Study meta-data:

https://www.irs.gov/statistics/soi-tax-stats-charities-other-tax-exempt-organizations-study-metadata