Assuming that the contribution was not an excess contribution, if the IRA contribution was entirely a nondeductible contribution to a traditional IRA it's correct the Form 1040X column B would be all blank unless the contribution resulted in additional Retirement Savings Contributions Credit on Form 8880. If this is the case, the only purpose for the Form 1040X is to provide explanation for filing Form 8606. The instructions for Form 8606 are ambiguous with regard to filing Form 8606 only to add a nondeductible traditional IRA contribution to a previously filed tax return, so some IRS examiners question the inclusion of Form 1040X while a few will question its absence under these circumstances. If the only reason for the Form 8606 is to add a nondeductible traditional IRA contribution to an already filed tax return, most people just send a signed Form 8606 with a separate explanation statement and no Form 1040X.
