What does a provisional patent application do?
As suggested in its name, the “provisional” in provisional patent application has a connotation of temporary or conditional. A provisional application is, by nature, short term. Something further must be done to make the temporary patent rights permanent, and that something is the filing of a nonprovisional patent application. The purpose of a provisional application, therefore, is to provide support for the nonprovisional application to be filed later. It defeats the purpose of filing a provisional application if this initial filing provides little support for a subsequent filing.
The USPTO website has a helpful overview on provisional patent applications.
How well can you write?
If the point of a provisional application is to support the later-filed nonprovisional application, you must consider the depth and breadth of the disclosure included in your provisional application. Have the key features been explained in gory detail? Have illustrations been provided where helpful to visualize the concept and any distinguishing characteristics?
If a picture is worth a thousand words, then perhaps you should include more visuals that help illustrate your concept. You can argue that support for a feature was disclosed in an image even if the written description failed to elaborate on it. If you intend to write the provisional application yourself, then understand what you should include to make the provisional more reliable.
Tradeoffs between provisional and nonprovisional applications
A direct relationship exists between the quality of a patent writing and the time spent. It is generally unrealistic to expect the same patent attorney or IP firm to draft the substance of a nonprovisional application and charge a fraction of the price by calling it a “provisional” application. For a substantial reduction in cost, something has to give.
If someone wanted to sell you a “new” luxury car that normally retails for six figures for the very affordable price of $1,000, your spider sense should go way up. Common sense would dictate that you generally get what you pay for. And if you pay $1,000 for a provisional application, you ought not expect to get $10,000 worth of patent drafting. Does a 90% cost savings magically appear because a patent document is called “provisional” instead of “nonprovisional”?
So if you save 90% of the cost of a nonprovisional application, what could possibly be missing in the provisional application? Are you willing to risk a later filing date for all the new subject matter that must be added to the subsequent nonprovisional application?
How does a priority date benefit work between provisional and nonprovisional applications?
A priority claim links a nonprovisional application to a previously filed provisional patent application. This connection gives the later-filed nonprovisional application the benefit of the earlier-filed provisional application. This benefit is called a priority date. How does the priority date benefit work?
The priority date comes into play when the examiner reviews the claims in the nonprovisional application. In particular, the examiner will search the prior art to evaluate each claim. Dates are important when determining whether a patent reference qualifies as prior art. If your claim is entitled to an earlier priority date, certain prior art references may be disqualified which means that the examiner would not be able to use those disqualified references to reject your claims.
Therefore, you want your provisional application to be sufficiently detailed to support the claims in your nonprovisional application. If key details are lacking in the disclosure of the provisional application, the examiner might argue that support for a particular claim is not found in the provisional application and that claim should be afforded a later date. Later dates generally open the door for more prior art references to be cited against you.