SUMMARY OF IRS LINK https://www.irs.gov/uac/like-kind-exchanges-under-irc-code-section-1031
You cannot sell ANYTHING and defer taxes…
You can EXCHANGE (qualified intermediary is hired.. you don’t get your hands on the money)… subsequent property is identified within 45 days… and have a total of six months from sale date to purchase like kind property.
When the exchange is done, if you received boot (money, cars, debt forgiveness in excess of debt assumed), then you are taxed on a part of the boot.
The old rules of selling a primary and reinvesting the proceeds in a home of equal or greater value are gone.
AND, it did not apply to a vacation home anyway, only a primary.