The letter should say what schedule is missing or what needs to be verified.
Please read over the letter to see exactly what they are asking for.
Below is from IRS web site on the LTR 12C.
- Missing forms or schedules to support your entries on Form 1040.
- Verification of income, withholding, and credit amounts
- Documentation to reconcile advance payments of the Premium Tax Credit (PTC). Please refer to PTC page for more information about letters regarding advance payments of the PTC.
- Read your letter carefully and respond timely.
- Respond to the letter, even if you disagree with the information in the letter. If you disagree, send us a letter explaining what information you think is in error. Provide the information requested in the letter.
Your letter 0012C provides a fax number, if you want to send the information by fax. If you prefer to mail your response, send the information to the address listed at the beginning of the letter. Also, include a copy of the letter with your response.You may want to
- Visit our Affordable Care Act page for more information about filing a tax return with Form 8962.