Retirement tax questions

You said "1040A line 12b " - that is a 2017 tax return.  There is no 2018 1040EZ and line 12bo on the 2018 1040 is Schedule 3 entries.

For a 2018 excess deferral returned in 2018 enter it this way:

You do not need to wait for a 1099-R next year that will probably require you to amend your 2018 tax return to report the
excess on line 1 of your tax return - it can be entered this way and then ignore the 2019 1099-R with a code P in box 7 when it comes.

There are two methods to do this:
1) Enter a 1099-R with the returned contribution amount (not including earnings) in box 1 & 2a, and a code "P" in box 7.   When asked what year 1099-R say 2019.

or 2)
Excess 401(k) deferrals should be reported in:
(There are several screens to click through to get to the right place)

Miscellionious Income ->
Other Income not reported on a W-2 ->
Other wages (yes) ->
House Hold employee (Continue) ->
Sick Pay (Continue) ->
Other earned income (yes) (Includes excess salary deferrals)->
Source of income (other) ->
Any other income - enter the amount of the excess deferral and an explanation.

This will add the returned excess to your 2018 wages on line 1 exactly the same way that the 1099-R would.  The only information that is sent to the IRS is the line 1 amount.

[Note: If there were any earning that were returned in 2019 then the earnings will be reported on a separate 2019 1099-R with a code 8 that goes on your 2019 tax return - do  not enter the earnings here.]

Both methods will add the returned excess to your 2018 wages on line 1 exactly the same way that the 1099-R would.  The only information that is sent to the IRS is the line 1 amount.

For information see IRS Pub 525 page 10
<a rel="nofollow" target="_blank" href="https://www.irs.gov/pub/irs-pdf/p525.pdf">https://www.irs.gov/pub/irs-pdf/p525.pdf</a>