Autofill Act of 201 9 This bill requires the Department of the Treasury to establish a program to allow taxpayers to download income tax forms that are populated with tax return information (e.g., wages, withholding, and self-employment income) previously reported to Treasury for the taxable year. By October 31, 2019, Treasury must: (1) establish standards for data download to tax preparation software, and (2) provide a demonstration server for downloading the partially populated printable document file. By February 15, 2020, and annually thereafter, Treasury must a provide a secure function on its website that allows a taxpayer to download, as both a printable document file and in a form suitable for input to automatic tax preparation software, the 1040, 1040A, and 1040EZ forms that are populated with tax return information previously reported to Treasury. The bill also establishes deadlines for reporting tax return information to Treasury and for making such information available for populating tax returns.