One of my items on a 1099-B was marked as Box X. The form had the date of sale and proceeds. I calculated the cost basis using my records and the stock was held long term. I entered it in TurboTax but chose Box D or E. After e-filing I was prompted to print and mail in Forms 8453 and 8949 for a different stock sale. I since learned the definition of the different boxes (https://ttlc.intuit.com/questions/3841864-vanguard-1099b-sale-category). Should I amend my return to use box F instead or is it OK as is?
