37 CFR §1.115

1. (a)A preliminary amendment is an amendment that is received in the Office (§ 1.6) on or before the mail date of the first Office action under § 1.104. The patent application publication may include preliminary amendments (§ 1.215(a)).
   1. (1)A preliminary amendment that is present on the filing date of an application is part of the original disclosure of the application.
   2. (2)A preliminary amendment filed after the filing date of the application is not part of the original disclosure of the application.
2. (b)A preliminary amendment in compliance with § 1.121 will be entered unless disapproved by the Director.
   1. (1)A preliminary amendment seeking cancellation of all the claims without presenting any new or substitute claims will be disapproved.
   2. (2)A preliminary amendment may be disapproved if the preliminary amendment unduly interferes with the preparation of a first Office action in an application. Factors that will be considered in disapproving a preliminary amendment include:
      1. (i)The state of preparation of a first Office action as of the date of receipt (§ 1.6) of the preliminary amendment by the Office; and
      2. (ii)The nature of any changes to the specification or claims that would result from entry of the preliminary amendment.
   3. (3)A preliminary amendment will not be disapproved under (b)(2) of this section if it is filed no later than:
      1. (i)Three months from the filing date of an application under § 1.53(b);
      2. (ii)The filing date of a continued prosecution application under § 1.53(d); or
      3. (iii)Three months from the date the national stage is entered as set forth in § 1.491 in an international application.
   4. (4)The time periods specified in paragraph (b)(3) of this section are not extendable.