Go to https://www.irs.gov/forms-instructions and query the system for the various 1040 forms and schedules and instructions. I save them in a folder each year to print out and fill out with pencil. Once I'm satisfied I've got the figuring right I go to Free Fillable Forms to set up an account (you need a new on every year, but you can use exactly the same logon and password, etc, as previous years) and enter my information. After every few entries go to the bottom and click "do the math."