By far the most common use I have for dates is filling out forms. In those cases the year is almost always essential. Speaking from personal experience, even a

By far the most common use I have for dates is filling out forms. In those cases the year is almost always essential. Speaking from personal experience, even an American can make an effort to use YYYY-MM-DD in any situation asking for a numeric date, and almost always succeed. The biggest exceptions are forms asking for MM/DD, and online payment forms asking for credit card expiration as MM/YY.