On the screen that precedes Select any less common adjustments that apply, is the screen Any of these less common items and it is here that you can enter your accrued market discount. After selecting Done, you should see the screen Select any less common adjustments that apply which you referenced in your post. The last item on that screen should already have a check mark, and the option to adjust your basis should also be there as well. If you add a positive amount that will increase your gain, and if you enter a negative amount, that will increase your loss.
You are correct in that all market discount recognized as income, whether currently or when you sell/redeem, will be added to the basis of your bond when you are figuring gain or loss. If you elect to currently include in income the market discount on a bond, increase the basis of the bond by the market discount that has been included in income for that bond.
@bobp55
**Say "Thanks" by clicking the thumb icon in a post
**Mark the post that answers your question by clicking on "Mark as Best Answer"
