A 401(k) is not an IRA so the IRA/SEP/SIMPLE box is not needed - leave it blank. A direct 401(k) rollover with a zero in box 2a will probably also have a code "G" in box 7. The box 5 being the same as box 1 indicates that this is after-tax basis that is being rolled into a Traditional IRA. You will want to keep track of that basis so that when you take a distribution from the IRA you can enter any existing after-tax basis already in the Traditional IRA and add this basis to it. The total after-tax basis will prorate the taxable amount of the distribution over the total value of the IRA and report that on a 8606 form. There will be an explanation as what the basis is being adjusted - say that it is after-tax 401(k) contributions that was rolled into the IRA.
It is not necessary to send a 8606 until you take a distribution from the IRA even if that is years in the future - so just keep track of it. I would keep the 1099-R's with the tax return forever so you have proof of the rollover and basis.
I am assuming that you have a 2nd 1099-R that rolled over the remainder of the 401(k) that is the same but nothing in box 5, which would be the before-tax money. 401(k) rollovers that contain both before-tax and after-tax money are often done on separate 1099-R's.
**Disclaimer: This post is for discussion purposes only and is NOT tax advice. The author takes no responsibility for the accuracy of any information in this post.**
