The Migration Data Users guide provides a detailed description of the State-to-State, County-to-County, and Gross Migration files produced by the Internal Revenue Service (IRS) Statistics of Income (SOI) Division. IRS Migration data for the United States are based on year-to-year address changes reported on individual income tax returns filed with the IRS. They present migration patterns by State or by county and are available for inflows—the number of new residents who moved to a State or county and where they migrated from, and outflows—the number of residents leaving a State or county and where they went. The data also include tabulations on the number of non-migrant returns within a State or county.
The Statistics of Income (SOI) Division’s State data is tabulated using individual income tax returns (Forms 1040) filed with the Internal Revenue Service (IRS) during the 12-month period, January 1 to December 31.