Probably not. A 501(c)(6) trade association must be organized to promote a common business interest of its members and has a prohibition, like a 501(c)(3) charity, against private inurement of any private shareholder or individual. A division of your tax-exempt “profits” from the vendors would most likely trigger that prohibition against private benefit to your members and you could lose your exemption. The test is not whether your members would pay an income tax on the rebate, but whether the organization itself is living up to its own tax requirements.