I filed my return which included schedule D and form 8949. Some of RSUs were vested in 2017. In both cases taxes were collected and income reported on W2. I had no stock options that were exercised last year. So, I am surprised why IRS wants me to file 6251.

There is one thing I am wondering I might have missed. In 2016, I received some shares in a startup and I had to file form 83(B). Is that why IRS is asking me to file form 6251? I am confused. I really appreciate any help.