If the business is an S-corp, a C-corp, an LLC with more than one member, or a partnership with someone other than your spouse, then the business must file a separate business tax return, using Turbotax Business. This is not the same as Home & Business or the Self Employed version. Turbotax Business is only available as a CD or download to install on a PC, there is no online or Mac version. The business tax return will create a K-1 statement for each owner or partner that is reported on their personal tax return. This also applies if you have an unincorporated sole proprietorship and make an election to be treated for tax purposes only as an S-corp. Note that business returns are due March 15, not April 15, and the late fee is $195 per month per partner.
For a sole proprietorship (either unincorporated, or single member LLC) this is treated as a disregarded entity by the IRS. You report your business income and expenses on a Schedule C which is part of your personal tax return. Schedule C lists the business income and expenses and determines the net profit. That profit flows to the main 1040 where it is combined with your other income, dependents and personal deductions, to calculate your overall income tax due. The profit from schedule C also flows to schedule SE to calculate self-employment tax (the self-employed version of social security and medicare withholding). Your total tax bill is your income tax plus self-employment tax. You would need Turbotax Self-Employed if filing online, or any version Deluxe or higher if using the CD or download software (the Home & Business version has the most built-in guidance, but the cheaper Deluxe version will do a schedule C if you know how to use it.)
Typically, you will file a joint return with your spouse that lists your regular jobs and includes a schedule C for your business. If you insist on filing the business separately, you have two choices. 1, make the election to treat the business as an S-corp for tax purposes. You then file a 1065 return for the business and include your K-1 on your personal tax return with your spouse. Or 2, file your personal return with schedule C as "married filing separately" and your spouse files their return as "married filing separately" also. But, MFS almost always results in higher taxes since many deductions and credits are reduced or disallowed for MFS taxpayers.
