Hard to say how often, but I recall when I mailed mine in the first week of January, they updated one of the forms the next week without warning. To know if they've been updated, look at the bottom of the forms for the version(month and year). If the forms you've completed have the same month and year as on the website, then you are using the current version of the forms and can submit. If it's different, then better to complete the newly updated forms.
Once you mail the package, if there's any update after, you don't have to worry. If they need a new form completed, they will send a request.
moonandtheriver said:
How often do they update the forms? How do I know if they've been updated? I didn't even know that was something I had to have on my radar. Ugh.