This is actually a significant issue, not only for accessibility but also for everyone's convenience. If you were to actually follow the original suggestion of "01 - January", "02 - February", etc., then someone probably has to click into the menu and click the month, or tab into the menu and scroll down to the month, or press 0 nine times to get to September. This is the worst scenario, and it makes me miserable when I have to do similar things all the time at work (which I do). "J" for January, "F" for February, "JJ" for June, "JJJ" for July, etc., is one option; 1 for January, 2 for February, 11 for October, 111 for November, etc., is another. In either case, you need no more than 4 keystrokes to get to the month you mean, at least with many browsers. The expiration day should probably be a type-in field. Unrelatedly, when websites ask for birth years and offer drop-down menus going all the way back to 1910 and all the way up to the present (as though newborns browse the web), that tends to be much more painful than just typing the year.