Many agencies have issued a warning that in the year 2020 you should write out “2020" while signing and dating legal documents.
So, it should always read “1/1/2020" rather than “1/1/20.”
The reason behind this is by using “20" as an abbreviation, extra numbers can easily be tacked onto the end to modify the date on the document. This can leave consumers vulnerable to fraud and other scams.