1. Short title This Act may be cited as the Stamp Out Invasive Species Act . 2. Combating invasive species semipostal (a) Finding Congress finds that invasive species pose a serious threat to our natural ecosystems, significantly harm native plant and animal populations, and cause detrimental economic damage to local communities. (b) Semipostal In order to afford a convenient way for members of the public to contribute to programs that combat invasive species, the United States Postal Service shall issue a semipostal stamp in accordance with the provisions of this section. Such semipostal stamp shall be known as the Combating Invasive Species Semipostal Stamp . (c) Terms and Conditions (1) In General The issuance and sale of the Combating Invasive Species Semipostal Stamp shall be governed by the provisions of section 416 of title 39, United States Code, and regulations issued under such section, subject to the requirements of this subsection. (2) Differential rate The differential included in the rate of postage established for the Combating Invasive Species Semipostal Stamp under section 416(c) of such title may not exceed 25 percent. (3) Duration The Combating Invasive Species Semipostal Stamp shall be made available to the public for a period of 2 years, beginning not later than 12 months after the date of enactment of this Act. (4) Disposition of Proceeds All amounts becoming available from the sale of the Combating Invasive Species Semipostal Stamp (as determined under section 416(d) of such title) shall be transferred in equal proportion to the Department of the Interior and the Department of Agriculture, for the purpose described in subsection (a), through payments which shall be made at least twice a year. (d) Definition For purposes of this Act, the term semipostal stamp means a stamp described in section 416(a)(1) of such title.