Obviously the IRS regulations (laws) are correct. The requirement is that one must live in the home as one’s primary residence for two years (731 days) out of a 5 year period ending on the day of the sale. The two years (731 days) do not have to be consecutive but must occur within 5 years of the sale date.
There is an exception or extension for military and certain others who moved as a result of foreign service orders, but you have never mentioned that before.
