M.G.L. Chapter 59 Section 11 states the name of the owner of the record as of January 1 will appear on the tax bill for the next fiscal year. The "C/O" in front of your name means Current Owner.
For example: if the property was sold on September 1, 2022, the previous owner's (known as the owner of record) name will appear on the top line of the actual bill that is issued on January 1, 2023. C/O will appear next to the new owner's name on the second line of the bill. The prior owner's name would be removed from the tax bill with the new fiscal year which starts on July 1, 2024.