I’ve seen more than one article recommending that, when we (meaning the public generally and not just lawyers) write the year on checks and other documents, we should write out the whole year, “2020,” and not just the last two digits, “20.”

The reasons is that, if you write only “20,” the date can be altered by just adding two more digits at the end, so that “20” could easily become “2019” or “2021.” (There was reportedly a similar concern in 1919.)

I’m not sure what advantage there could be in backdating (or postdating) a check by one year, but writing out the full year does no harm, and takes very little in the way of time or ink (or printer toner), and so seems like a good idea.