You should receive Form 1099-R from the financial instutiion where the 401(k) funds were held.
The 1099-R will report the distribution from your 401(k) as a partial rollover, which means that that portion will not be taxable (unless it was rolled into a Roth IRA). The amount that you received will most likely be shown in box 2 as the taxable portion.
You should not report the rollover separately as an IRA contribution, as this will trigger problems with the contribution amount.
Note: All 1099-Rs must be placed in the mail by January 31, 2017. If you do not receive your 1099-R by February 10, contact the financial institution that was handling your 401(k).
