An individual retirement account is a good choice for a rollover of 401(k) funds. An IRA allows the funds to continue to grow with taxes deferred. Every time you move money out of a retirement account, however, you must report the transaction to the Internal Revenue Service. When you roll funds from a 401(k) into an IRA, you report the action on your Form 1040.
Look for your Form 1099-R -- reporting the amount that has been rolled over from the 401(k) to the IRA -- to arrive by mail. You should receive it in late January or early February.
Find the total amount of your rollover in Box 1 of Form 1099-R. Enter that amount on Line 16a of IRS Form 1040.
Find the taxable amount of the rollover in Box 2a of Form 1099-R. Enter this amount on Line 16b of Form 1040. If you effected a direct rollover from one trustee to the other, this amount should be 0.