Quality Systems Inc. and Questcor Pharmaceuticals Inc. said today that they plan to pay their shareholders dividends earlier than previously scheduled because of uncertainty over tax rates for 2013.

Irvine-based healthcare software maker Quality said it would pay a 17.5-cents-a-share quarterly dividend to shareholders on Dec. 28 instead of its previously announced Jan. 4 date.

Questcor, an Anaheim-based drug maker, said it would pay a 20-cents-per-share dividend on or about Dec. 21. The maker of H.P. Acthar Gel would have paid the dividend in the first quarter of 2013.

Questcor said in a release that it moved up its dividend payment date in order to allow current shareholders to benefit from the current dividend tax that’s scheduled to expire Dec. 31.