Deductions & credits

This tax owed was deferred to be payed later by my CPA who filed my 2018 taxes for me. He also told me that I will avoid owing this tax if I spend the amount owed or more on replacement housing expenses. Since I plan to purchase a replacement home in 2020, I would like to defer the amount owed on my 2019 taxes but I don't know how to accomplish this. My CPA said he simply filed a note with my taxes and was not willing to explain in detail how I can do this myself.