Filing a provisional makes sense when you have limited funds and you want to take advantage of the relatively new “first to file” rules implemented under the America Invents Act, perhaps as importantly, when you have a “bar date” approaching (i.e., if you don’t file before or on the bar data your lose your rights). When you publicly disclose, publicly use, publish, sell, or offer your invention for sale, it creates a bar date that affects your ability to get a patent for your invention (see 35 USC §102). The US offers a 1-year grace period, but you must file within that year.

Please note, however, that a provisional application is not a “shortcut” or a “down & dirty” application that can hold the place for a later-filed non-provisional utility patent application, unless it “sufficiently” discloses the invention under 35 USC 112(a).  That is, the provisional application must be competent (it must evidence to one of ordinary skill in the art pertaining to the invention) that the inventor(s), at the time of filing the provisional application, had possession of the invention as claimed in the issued patent that evolved from the non-provisional utility patent application, which itself evolved from the provisional.  If the claims that issue include something added during preparation of the non-provisional utility patent application, or otherwise end up in the claims during prosecution, and the same claim feature must be relied upon to distinguish prior art (for example, if the patent is challenged in a litigation) found to be available within one year prior to filing the provisional, the validity of the patent may be on shaky ground (please call to discuss in further detail).