Not all payouts to shareholders are "qualified dividends," but those that are get favorable treatment in which they're normally taxed at less than your rate for ordinary income.

But the tax rules for qualified dividends may go out the window if proposed tax reforms are enacted. The big question is whether you would fare worse under the new rules—or better.

Under current law, most dividends issued by domestic companies are qualified when paid out to shareholders and the owners of mutual funds. In some cases, qualified dividends also may come from foreign corporations, if their shares include publicly traded American Depositary Receipts (ADRs) or shares that are otherwise readily available on an established U.S. securities market.