Iowa Department of Revenue spokesperson, Victoria Daniels,says you should be prepared to pay a penalty of an extra 10 percent on top of whatever you owe if you file late. “I will say that typically there is a very slight grace period. But I encourage people strongly to get their returns in and file them electronically. And make their payments no later than 11:59 p.m.,” Daniels says.
If you don’t have enough money to pay your entire tax bill, Daniels says you should attempt to pay at least 90 percent of what is owed. As long you meet the 90 percent threshold, you can avoid a penalty and pay the rest later with interest.