A few municipal bonds I inherited either matured or were called in 2020. The cost basis reported on my monthly brokerage statements (which shows the purchase date as the date of my father's death) reflect a different basis each month. On the 1099-B, the brokerage lists the cost basis at redemption value, but I read that I should adjust the cost basis to the basis at time of death. Should I use the cost basis as shown when first transferred to my account or the cost basis reflected on the 1099-B? Thank you.