A provisional patent application lasts exactly 12 months from the day you file it, and that deadline cannot be extended for any reason. Once the 12 months pass, the application automatically expires, whether or not you were still working on your invention. If you want to keep the earlier filing date, you have to file a non-provisional utility application before that window closes.
That single rule shapes almost everything about how inventors use provisional applications. Here’s what it actually means in practice, and what happens if you let the clock run out.
The 12-Month Rule, Explained
A provisional application is filed under 35 U.S.C. §111(b) and is never examined by the USPTO. It exists purely to secure an early filing date and let you use the term “patent pending.” From the moment it’s filed, the countdown starts, and it runs for precisely 12 months, not a rough estimate or a flexible window.
There’s no renewal option and no way to pay a fee to buy more time. The USPTO treats this deadline as fixed by statute, which means it applies the same way to every applicant regardless of the invention or the reason for the delay.
What Happens on Day 366
If you haven’t filed a corresponding non-provisional application by the end of the 12 months, the provisional application becomes abandoned automatically. You don’t receive a formal rejection or a chance to explain. The filing simply stops being active, and the priority date attached to it is gone.
Can You Get Any Extra Time at All?
There’s one narrow exception. If you miss the 12-month deadline but file your non-provisional application within 14 months of the original provisional filing date, you may be able to restore the benefit of that earlier date. This requires filing a petition under 37 CFR 1.78, including a statement that the delay was unintentional, along with the required fee.
This isn’t an extension of the provisional itself. It’s a narrow safety net for applicants who miss the deadline by a small margin, and it only works if the delay genuinely was unintentional. Once you pass the 14-month mark, there’s no remaining path to recover that original filing date.
What Filing a Non-Provisional Application Actually Does
Filing a non-provisional application before the 12 months expire doesn’t extend the provisional. Instead, it lets the new application claim the benefit of the provisional’s earlier filing date under 35 U.S.C. §119(e). The provisional application itself still expires at 12 months. What carries forward is the priority date, not the provisional filing.
The non-provisional application must specifically reference the provisional it’s claiming priority from, and this reference has to appear in an application data sheet. Missing that reference can mean losing the benefit of the earlier date even if you filed on time.
Converting a Provisional Into a Non-Provisional
Instead of filing a brand-new non-provisional application, you technically have the option to convert the provisional application itself into a non-provisional one. Most patent professionals advise against this. Conversion effectively shortens the resulting patent’s term, since a 20-year patent term is measured from the earliest non-provisional filing date, and treating the provisional as that filing date starts the clock earlier than it needs to.
Filing a separate non-provisional application that simply claims priority to the provisional almost always preserves more patent term and is the more common route.
Provisional Application Timeline at a Glance
| Milestone | Timing | What It Means |
|---|---|---|
| Provisional filing date | Day 1 | Priority date is established; “patent pending” status begins |
| Standard deadline to file non-provisional | 12 months | Required to keep the provisional’s priority date |
| Petition window to restore priority | Up to 14 months | Available only with proof the delay was unintentional, plus a fee |
| Automatic abandonment | After 12 months (no petition filed) | Provisional expires permanently; priority date is lost |
| Non-provisional patent term | Up to 20 years | Measured from the non-provisional filing date, not the provisional |
Why the Deadline Catches People Off Guard
Twelve months sounds like plenty of time when you first file, but it moves faster than expected once you’re testing prototypes, lining up manufacturers, or raising money. A few habits help avoid missing it:
- Mark the exact filing date and set reminders several months, not weeks, ahead of the deadline
- Start drafting the non-provisional application well before the final months of the window
- Budget for the higher cost of a non-provisional filing early, rather than scrambling at the last minute
- Talk to a patent attorney or agent early enough that formal claims and drawings can be prepared properly
This article is provided for general informational purposes only and is not legal advice. Patent deadlines and procedures can vary based on your specific circumstances, so it’s a good idea to consult a registered patent attorney or agent before making filing decisions.
Frequently Asked Questions
Does a provisional patent ever turn into a real patent by itself?
No. A provisional application can never mature into a granted patent on its own. It only becomes useful if you file a non-provisional application that claims its priority date within the 12-month window.
Can I file a second provisional application to reset the clock?
You can file a new provisional application, but it won’t extend or restore the original filing date. The new provisional gets its own separate 12-month period starting from its own filing date.
What happens to my invention if the provisional application expires unused?
Once it expires, the application is abandoned and can’t be revived. You can still file a new patent application later, but you lose the earlier priority date, and anything you disclosed publicly in the meantime could affect your ability to patent it.
Is the 14-month restoration petition guaranteed to work?
No. It requires a grantable petition under 37 CFR 1.78, a statement that the delay was unintentional, and the applicable fee. Approval isn’t automatic, and the option disappears entirely after 14 months from the original filing date.
Does filing a non-provisional application early use up any of my 12 months?
No. You can file the non-provisional application at any point during the 12-month period, including shortly after the provisional itself. Filing earlier doesn’t shorten your rights and can reduce the risk of missing the deadline.