For box 12 there is a “D” in 12a and a “DD” in 12b but the drop down selection only gives the option to select one or the other for box 12

[TomK100]

The W-2 you got from your employer will have four lines for Box 12 — labeled 12a, 12b, 12c, and 12d.

Any amount on a Box 12 line will also have an upper-case (capital) letter code associated with it. (If there aren’t any capital letter codes in Box 12, skip it and move on to Box 13.)

In each Box 12 line, simply select the capital letter code from the drop-down list and enter the corresponding amount. See the example a bit further down to see what it would look like in the TurboTax CD/Download software.

Important: Don't confuse the lower-case Box 12 letter (for example, the a in Box 12a) with the capital letters in the drop-down list. So, if your Box 12a has the letter code D in it, select D (not A) from the drop-down list. And if 12a is blank, leave it blank — don't select A.

To enter multiple Box 12 amounts in TurboTax Online, select +Add another row. In the software, additional Box 12 lines will appear when the preceding lines are full.

[AsianShadowNinja]

I think my taxes were filed incorrectly even after I added this, what do I do?

[DawnC]

If you need to make a correction after filing your tax return, you would need to file an amended return.  First, verify that you return has been filed and accepted, see link below for instructions.  If it has not been accepted yet, you can make the changes and submit your return.  You only need to file the amendment if there is an error that causes the final numbers to change and your return has already been accepted.  

You can amend e-filed returns if they've been accepted; paper-filed returns may be amended once they've been mailed.

If your e-file is still pending, you won't be able to make changes until the IRS either accepts or rejects it. Don't know your e-file status? Here's how to look it up.

Select your tax year for amending instructions:

• 2019
• 2018
• 2017
• 2016

Keep in mind: You have 3 years from the date you filed your return or 2 years after you paid the tax due (whichever is later) to file an amendment.

Related Information:

@AsianShadowNinja

• What does it mean to "amend" a return?
• Do I need to amend?
• Will amending delay my original tax refund?
• What is the deadline for filing an amended return?
• Can I e-file my 1040X to amend my return?
• The Bipartisan Budget Act of 2018 - what's in it for you