Who does your taxes?  H&R Block?  TurboTax?  A CPA/Tax Professional?  Yourself?  Check out this web map by ESRI.  ESRI says it used data at the census tract and block group level. It looked at whether taxpayers used H&R Block, TurboTax, a certified public accountant or other tax professional, or did their taxes on their own. ESRI then credited that block to which ever method was used the most.  Click on a point and get the breakdown of tax methods.