I agree with
@jeffelm1's answer. If it was Vanguard's error and you checked the 2015 box on the contribution form (if they gave you one to fill out), then only Vanguard can reissue a corrected 5498 form to report to the IRS a change in tax years for the contribution.
**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.**
