Under 37 CFR 1.136, extensions of time to respond to a patent office action come in two forms: an automatic extension of up to five months that you buy by paying a fee, and a discretionary extension granted only for sufficient cause when the automatic route isn’t available. Both live under a hard ceiling set by 35 U.S.C. ยง 133: no response filed more than six months after the office action’s mailing date will be accepted, and the application will be treated as abandoned.1Office of the Law Revision Counsel. 35 USC 133 – Time for Prosecuting Application
The Automatic Extension Under Paragraph (a)
Paragraph (a) is the path most applicants use. You file a petition, pay the fee, and the extension is granted. No justification, no explanation, no discretion involved.2eCFR. 37 CFR 1.136 – Extensions of Time
What matters is how the math works against the six-month cap. The six months runs from the mailing date of the office action, not from the end of the reply period the examiner set, and not from any extension you buy. So if the examiner gave you a two-month reply period, you can add up to four months on top (landing at six). A three-month reply period leaves room for three more months, not five. The ceiling is absolute.
Two situations paragraph (a) will not fix: it does not apply to provisional applications, and it cannot revive an application that has already gone abandoned. Once the deadline passes without a timely response or a timely extension in place, you’re in different territory (see below).
What the Extension Costs
The fee for an automatic extension rises steeply with each additional month. Current rates under 37 CFR 1.17(a):3United States Patent and Trademark Office. USPTO Fee Schedule
- One month: $235 large entity / $94 small / $47 micro
- Two months: $690 / $276 / $138
- Three months: $1,590 / $636 / $318
- Four months: $2,495 / $998 / $499
- Five months: $3,395 / $1,358 / $679
These are per-extension fees, not cumulative. A three-month extension costs $1,590 for a large entity, not the sum of the one-, two-, and three-month tiers. Small entities receive a 60% discount and micro entities an 80% discount on most patent fees, extensions included.4United States Patent and Trademark Office. Save on Fees with Small and Micro Entity Status
The Hidden Cost: Patent Term Adjustment
The fee is not the full price. Under 37 CFR 1.704(b), the USPTO reduces your patent term adjustment day-for-day for any time you take beyond three months to respond, whether or not you paid for an extension.5eCFR. 37 CFR 1.704 – Reduction of Period of Adjustment of Patent Term
The three-month clock starts on the office action’s mailing date. The examiner’s stated reply period doesn’t change it. If the examiner set two months and you buy a one-month extension, you respond at three months with no PTA loss. Buy a two-month extension and respond at four months, and you lose roughly 30 days of patent term. Take the full six months and you lose about 90 days off the back end.6United States Patent and Trademark Office. Manual of Patent Examining Procedure Section 2732 – Reduction of Period of Adjustment of Patent Term
For patents where every month of exclusivity has real commercial value, the strategic calculus changes. A $235 one-month extension that keeps you at three months is very different from a $1,590 three-month extension that shaves 30 days off your patent’s life.
How to File
Most applicants file automatic extensions using Form PTO/SB/22, a fillable PDF on the USPTO website. It asks for the application number and filing date, a box checked for the number of months, and payment authorization.7United States Patent and Trademark Office. Petition for Extension of Time Under 37 CFR 1.136(a) In practice, the extension petition and the substantive response are filed together so the response is treated as timely.
Filing goes through Patent Center, which handles the upload, the fee, and the electronic receipt in one interface.8United States Patent and Trademark Office. File Online The application’s status typically updates within a few business days to show the new deadline. Confirm that update; a processing error caught early is easy to correct.
Extensions for Cause Under Paragraph (b)
When paragraph (a) isn’t available, paragraph (b) offers a narrower path. It requires a showing of sufficient cause and is decided by the Technology Center Director on the facts of the individual case.2eCFR. 37 CFR 1.136 – Extensions of Time The petition must be filed on or before the day the reply is due, must include the fee under 37 CFR 1.17(g), and must explain in writing why the response could not be completed on time. Merely filing the petition does not extend the deadline; if the Director denies it after the deadline has passed, the application goes abandoned.
The USPTO does not publish a bright-line definition of sufficient cause. Practitioners generally understand it to cover circumstances genuinely outside the applicant’s control, such as a medical emergency involving the attorney of record or a natural disaster affecting operations. Heavy workload and scheduling conflicts are unlikely to qualify. A granted petition specifies the exact length allowed; a denial comes with a written reason.
Proceedings Where Automatic Extensions Don’t Apply
A few categories of patent proceedings sit outside paragraph (a) entirely. Ex parte reexamination follows its own timing rules under 37 CFR 1.550, which require sufficient cause for any extension and cap extensions at two months absent such a showing.9United States Patent and Trademark Office. Manual of Patent Examining Procedure Section 2265 – Extension of Time Interference proceedings operate under separate procedural rules. Provisional applications are excluded as well, since they receive no examination and produce no office action to extend a response to.3United States Patent and Trademark Office. USPTO Fee Schedule
If the Deadline Has Already Passed
Section 1.136 cannot revive an application that has gone abandoned. Revival requires a separate petition under 37 CFR 1.137, which asks for a statement that the entire delay was unintentional, the required reply to the outstanding office action if not already filed, and the petition fee under 37 CFR 1.17(m).10eCFR. 37 CFR 1.137 – Revival of Abandoned Application The “unintentional” standard sounds forgiving, but the USPTO can demand additional information if it doubts the claim, and longer gaps between abandonment and the petition tend to draw more scrutiny. Filing a 1.136 extension before the deadline is almost always cheaper and safer than trying to revive an application after the fact.