I sold a rental property in late 2021. After the tenants had moved out, and a buyer was interested, there was a sewer backup which cost about $15K to put back to the condition before the casualty. There were multiple contractors involved. One sent their bill to the wrong address, and in all the commotion I didn't notice I hadn't paid it. It was for $7K. Just before sending it to collections, they made more of an outreach effort which found me, and I paid it then, May of 2022. I added the bills I did pay in 2021 to the cost of selling. I believe the basis was reduced by the cost to restore it, and there was no time to depreciate it significantly differently from the rest of the asset, but I don't really understand this stuff.
I think I should just file an amended return before Tomorrow's 3 year deadline for 2021 with that $7K added to the cost of selling. And a distant relative who is a CPA told me to do that in a 30 second aside at a family reunion. But I've been unsure, and have procrastinated to the last moment, and am now asking for any advice
