The Starwood Preferred Guest American Express card, which yields points in the loyalty program for Westin, Sheraton and others, is offering double points on the first $5,000 of personal federal taxes paid. American Express Co. is giving away double Delta Air Lines miles on federal taxes too, but with a higher cap of 30,000 to 100,000 bonus miles depending on which Delta AmEx card that you use.

The cards are also offering separate 20% mileage bonuses on all base charges through April 30; register at americanexpress.com/deltabonus. With both bonuses, you'll earn 2.2 miles per dollar of tax charges. The United and American cards have tax-season promotions too.