For dividend reinvestment to be enabled, does it depend on both the company *and* the broker? Says here on the IRS publication page 21 that regardless of whether you receive cash or shares, it's taxable. The dividends section starts on page 19.

Dividends Used To Buy More Stock The corporation in which you own stock may have a dividend reinvestment plan. This plan lets you choose to use your dividends to buy (through an agent) more shares of stock in the corporation instead of receiving the dividends in cash. Most mutual funds also permit shareholders to automatically reinvest distributions in more shares in the fund, instead of receiving cash. If you use your dividends to buy more stock at a price equal to its fair market value, you still must report the dividends as income. If you are a member of a dividend reinvestment plan that lets you buy more stock at a price less than its fair market value, you must report as dividend income the fair market value of the additional stock on the dividend payment date

irs.gov/pu...50.pdf