Yesterday, the United States Patent and Trademark Office issued its final rules for Changes to Implement Micro Entity Status for Paying Patent Fees. The rules provide for the filing of a certificate of micro entity status once during the pendency of a patent application and patent, and the payment of micro entity fees can be made so long as micro entity status applies when the fee is paid. 35 U.S.C. §123(a) defines a “micro entity” as

an applicant who makes a certification that the applicant: (1) qualifies as a small entity as defined in 37 CFR 1.27; (2) has not been named as an inventor on more than four previously filed patent applications, other than applications filed in another country, provisional applications under 35 U.S.C. 111(b), or international applications for which the basic national fee under 35 U.S.C. 41(a) was not paid; (3) did not, in the calendar year preceding the calendar year in which the applicable fee is being paid, have a gross income, as defined in section 61(a) of the Internal Revenue Code of 1986 (26 U.S.C. 61(a)), exceeding three times the median household income for that preceding calendar year, as most recently reported by the Bureau of the Census; and (4) has not assigned, granted, or conveyed, and is not under an obligation by contract or law to assign, grant, or convey, a license or other ownership interest in the application concerned to an entity that, in the calendar year preceding the calendar year in which the applicable fee is being paid, had a gross income, as defined in section 61(a) of the Internal Revenue Code of 1986, exceeding three times the median household income for that preceding calendar year, as most recently reported by the Bureau of the Census. See 125 Stat. at 318.