Suggestion to just file correctly on paper seems likely at this point, but surely it is a simple slight change to make in Turbotax "Premier" to accomodate such prior-year contributions (also arising from court orders, etc, not just military). Please carefully read the IRS W2 Box 12 instructions for employees:
Box 12. The following list explains the codes shown in box 12. You may
need this information to complete your tax return. Elective deferrals
(codes D, E, F, and S) and designated Roth contributions (codes AA,
BB, and EE) under all plans are generally limited to a total of $19,000
($13,000 if you only have SIMPLE plans; $22,000 for section 403(b)
plans if you qualify for the 15-year rule explained in Pub. 571). Deferrals
under code G are limited to $19,000. Deferrals under code H are limited
to $7,000.
However, if you were at least age 50 in 2019, your employer may have
allowed an additional deferral of up to $6,000 ($3,000 for section 401(k)
(11) and 408(p) SIMPLE plans). This additional deferral amount is not
subject to the overall limit on elective deferrals. For code G, the limit on
elective deferrals may be higher for the last 3 years before you reach
retirement age. Contact your plan administrator for more information.
Amounts in excess of the overall elective deferral limit must be included
in income. See the instructions for Form 1040.
Note: If a year follows code D through H, S, Y, AA, BB, or EE, you made
a make-up pension contribution for a prior year(s) when you were in
military service. To figure whether you made excess deferrals, consider
these amounts for the year shown, not the current year. If no year is
shown, the contributions are for the current year.
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