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While this data can be used to study migration of households (using filers) or individuals (using exemptions) there are limitations with the data that users must be aware of: see our documentation (below), the IRS documentation (on their website and included with the database downloads), and other studies for examplesdetails. For example, not everyone files taxes, so the data does not represent every possible move. The IRS implemented a number of methodological improvements beginning in 2011-12 which would impact any comparisons made before and after that time period.
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