It's probably unnecessary to amend your tax return because the code 4g with a zero box 2a already indicates that you made a nontaxable rollover and the 2017 Form 5498 that will be issued by the inherited IRA will show the rollover contribution. However, be sure to retain all documentation necessary to support the position that the distribution was properly rolled over in case the IRS questions whether or not the rollover was actually completed. Some people manage to divert the distribution to an account other than a proper inherited IRA, so, absent recognition that the Form 5498 indicates that the rollover was completed, the IRS might assume that the rollover was not completed and the gross amount is subject to taxation.
