>that form allowed the company to then tax me on that ‘gift’ as income,
Wrong. There is no "form" needed for taxation, it is required by the IRS (in U.S.) and the company does not "tax" anyone. Employer gifts (other than de minimis amounts) are taxable compensation. (see IRS Publication 15-B for details).
A good employer will "gross up" cash gifts to cover the taxes.