Exhibit 99.3 CERTIFICATION PURSUANT TO SECTION 1350, CHAPTER 63 OF TITLE 18, UNITED STATES CODE, AS ADOPTED PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002 Pursuant to Section 1350, Chapter 63 of Title 18, United States Code, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, the undersigned, as an executive officer of the chairman of Allmerica Financial Corporation (the "Company"), does hereby certify that to the undersigned's knowledge: 1) the Company's Quarterly Report on Form 10-Q for the quarter ended September 30, 2002 (the "Report") fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and 2) the information contained in the Company's Report fairly presents, in all material respects, the financial condition and results of operations of the Company. /s/ Robert P. Restrepo, Jr. Robert P. Restrepo, Jr. Executive Officer of the Chairman Dated: November 14, 2002