No, the Form 4868 is only an extension of time to file your original return to eliminate late filing fees. This will not pertain in your situation. You can simply amend your return to include the necessary information.
To amend your tax
return use the information below and be sure to read it completely before you
begin so that your original figures are entered on the amendment appropriately.
The IRS does not allow the amended return to be e-filed therefore you must
mail the return. Instructions will be provided including the address.
Your state return should be included in the amendment if applicable. (see
images attached)
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