What can I do about new information (name and address) being included on my taxes before a name change has been finished?

My husband and I got married in November and I changed my information at my job thinking it would be finished by tax season, however that's not the case. There is a long-lived error with his last name which has often been an issue for him, and we are planning to fix it before I take his name. The process hasn't finished, yet on my W2 it has his last name with his along with the address that I've moved to, both of which aren't the same on my ID. I've been told by one of my coworkers to send in a letter to the IRS explaining the situation, but I don't know how true that information is or how to do it. We have just filed for an extension, I'm just hoping it won't take that long. How do I fix this in the easiest ways possible?