“May Day” has passed — and that means Iowa income tax deadline day is history. The Iowa Department of Revenue and Finance received about one-point-three million income tax returns by the deadline. Renee Mulvey, the tax agency’s spokeswoman, says there are some latecomers.Mulvey says there are about 100-thousand Iowans who haven’t filed their taxes yet. She says the state doesn’t have an extension form. Mulvey says if you’ve paid 90 percent of your taxes by May 1st, you get an automatic 6 month extension to pay the remaining ten percent.If you’re due a refund from the state, you must claim it within three years — or you forfeit the money.The number of Iowans who are filing their state income taxes electronically is increasing dramatically. Just under 28 percent — or 360-thousand Iowans used the electronic method of submitting their income tax returns to the state. By comparison, only 16 percent of last year’s Iowa income tax returns were “e-filed.” If you file your taxes electronically and you’re due a refund, you’ll get it in about half the time as you would using the traditional drop-it-in-the-mailbox method.