If a single member LLC, that is considered a disregarded entity by the IRS. All the income for each single member LLC are reported on SCH C as a physical part of your personal 1040 tax return. You will have one SCH C for each individual single member LLC business.
If a multi-member LLC, then each multi-member LLC must file it's own physically separate IRS Form 1065 Partnership Return. (For the IRS, the only difference between a partnership and a single member LLC, is the spelling.) Then each multi-member LLC will issue each owner a 1065 K-1 which each owner will need in order to complete their personal 1040 tax return.
If the LLC (be it single member or multi-member) filed form 8832 with the IRS to be "treated like an S-Corp" for tax purposes, then the LLC is not an LLC as far as the IRS (and *ONLY* the IRS) is concerned. It's an S-Corp. Therefore the LLC/S-Corp must file it's own IRS Form 1120-S Business tax return. The business will issue each owner of the businses an 1120-S K-1 which each owner will need to complete their personal 1040 tax return.
If this is a multi-member LLC/Partnership or S-Corp, then the 2018 tax return for that business was due on March 15, 2019. If you filed an extension for the business, then the due date is Sept 15th, 2019. The late penalty for filing late is $200 per owner/shareholder, per month. That would mean that if an extension was required but not filed, the late filing penalty is already up to $800 for each owner and gots to $1000 on Aug 15th, 2019.
