Retirement tax questions

Nope. Don't need to do that. You can still do the summary totals and make an adjustment for that one entry that shows in a Box E. Here is how. 

1. Open or continue your return (if it's not already open) and search for stock sales.
2. Select the Jump to link in the search results.
3. Answer Yes to Did you sell stocks, mutual funds, bonds, or other investments in 2020?.
   • If you land on Your investment sales summary, select Add more sales. 
4. On the OK, what type of investments did you sell? screen, select Stocks, Bonds, Mutual Funds, then Continue.
5. When asked how you want to enter your 1099-B, select I'll type it myself.
6. Answer the questions until you can select Enter sales section totals rather than entering sales one at a time.
7. When you begin entering summary totals, you will reach a screen that says sales section totals. then you will check a box that says I need to adjust my total cost basis 
8. Here you will put the amount that is in Box 1G and the adjustment code that follows. Here is what the screen looks like.