If you run the Tax Schedule Report, it returns a report that is off by one year. For example, if the report is run with start and end dates of 1/1/2018 and 12/31/2018, it returns a report for 2017. I was able to work around the problem by running my report for 2019, which gave me the 2018 report that I needed, but there's an issue there. Thank you for GNUCash. I appreciate it.
This is controlled by the "Alternate Period" option on the report options General tab immediately below the dates. It defaults to "Last Year" which makes sense if you have left the default From/To of start and end of the accounting period but perhaps not if you've explicitly selected a date range where "Use From - To" would be a better default, but you can select it yourself to get the result that you want.
