In computing unincorporated business taxable income, there shall be allowed (without allocation under section 11-508 of this chapter):
(1) an unincorporated business exemption of five thousand dollars, prorated for taxable years of less than twelve months under regulations of the commissioner of finance;
(2) if a partner in an unincorporated business is taxable under this chapter or under any local law imposed pursuant to section one of chapter seven hundred seventy-two of the laws of nineteen hundred sixty-six, an exemption for the amount of the partner's proportionate interest in the excess of the unincorporated business gross income over the deductions allowed under sections 11-507 and 11-509 of this chapter, but this exemption shall be limited to the amount which is included in the partner's unincorporated business taxable income allocable to the city, or included in a corporate partner's net income allocable to the city, provided, however, no such exemption shall be allowed to an unincorporated business for any taxable year of the unincorporated business beginning after June thirtieth, nineteen hundred ninety-four.