Or was "1040f" just a typographical error? Are you just asking about filing your tax return on Form 1040? For 2018 and onward, everyone is using a Form 1040. The old 1040EZ and 1040A forms are gone and the new Form 1040 is a "postcard" size form that is two half pages, with six possible schedules that go with it. You may need some or even all of the schedules, depending on what information you have to enter on to the tax return.
The tax forms are different for 2018 and beyond since the new tax laws went into effect. Everyone gets a "postcard size" Form 1040 that only goes to line 23. In addition, there are six possible extra pages called "schedules" that may be included as part of the tax return that you prepare and file.