USA Income Tax Data By ZIP Code, 2014

The Statistics of Income (SOI) division bases its ZIP code data on administrative records of individual income tax returns (Forms 1040) from the Internal Revenue Service (IRS) Individual Master File (IMF) system. Included in these data are returns filed during the 12-month period, January 1, 2015 to December 31, 2015. While the bulk of returns filed during the 12-month period are primarily for Tax Year 2014, the IRS received a limited number of returns for tax years before 2014 and these have been included within the ZIP code data.

There is data for more years here:

https://www.irs.gov/uac/soi-tax-stats-individual-income-tax-statistics-zip-code-data-soi

See documentation file attached. Crucially:

ZIPCODE - 5-digit Zip code
 

AGI_STUB - Size of adjusted gross income

1 = $1 under $25,000
2 = $25,000 under $50,000
3 = $50,000 under $75,000
4 = $75,000 under $100,000
5 = $100,000 under $200,000
6 = $200,000 or more