If you’re planning to fly the Eastern Seaboard on the cheap this month, don’t let this one pass you by. Until Dec. 15, Delta’s discount carrier, Song, is offering bonuses for roundtrip tickets purchased with an American Express card.

Registered SkyMiles members will earn 5,000 bonus miles for one, 5,000 more for two, and 10,000 more for three.

Qualifying purchases must be made on flysong.com.