Don't abbreviate 2020. It's for your own good

I second this. It is worth the short read!

Indeed. It has literally blown the minds of everyone I have mentioned this to since reading the article.

OTOH my sister thought it would also be a potential way to "prove" you don't even have to make a payment until sometime a year or years later. And she has a very good point: the risk goes both ways. As a consultant, I could theoretically get a customer who changes my invoice to another year and blames some rogue middleman for the error.