I misplaced the 1099R slip. How important is it to send a copy of it with my return? It is my understanding that the IRS is sent a copy so I'm wondering if it's ok to not include the slip as long as the info is on the return.
Most financial institutions have the 1099-R forms that they send to you online where you can get them in your account. Have you looked there?
If there was withholding on the form, you are required to mail it with your return. I don't know what the IRS will do if they get the return without the form showing the withholding.