If you fail to amend a return when you know it contains a mistake you may have to pay penalties if the return is audited. I recommend that you file an amended return as soon as possible. If you do not want to do it yourself you should choose a competent accountant or tax lawyer - don't use the tax prep office on the corner.
a 1040X can be used to amend returns.
Curt Harrington Patent & Tax Law Attorney Certified Tax Specialist by the California Board of Legal Specialization PATENTAX.COM This communication is general information and not legal advice, and does not create an attorney-client relationship. This communication should not be relied upon as any type of legal advice. Please note that no attorney-client relationship exists between the sender and the recipient of this message in the absence of either (1) a signed fee contract and (2) remission of an agreed-upon retainer. Absent such an agreement and retainer, I am not engaged by you as an attorney, nor is any other member of my law firm.
An amendment to your original tax return would be your best bet. If you call the IRS, they are going to tell you that you need to file a 1040 X as Mr. Harrington indicated.
This response does not create an attorney client relationship nor should the advice be relied upon because it is not specific to your legal situation. Before you depend on legal advice, you should retain competent counsel.