You may need to mail a paper return to the IRS or state agency if:
Before mailing the return(s), be sure to read the filing instructions. They will include important information such as where to file, what to attach to the return (i.e. W-2s, 1099s, etc.), refund or balance due, information about estimated tax payments, etc.
Note. File your return, schedules, and other attachments on standard size paper. Cutting the paper may cause problems in processing your return.
*Note. If you are paper-filing your return because you were rejected on the filing due date, you should also include an explanation and a copy of the IRS rejection with your paper return. This return would need to be mailed within 10 days of your rejection and no later than April 25th.