If "we" own an LLC, that makes it a multi-member LLC. A multi-member LLC files IRS Form 1065 Partnership/Multi-member LLC tax return. The return is due by March 15th (not Apr 18th like personal taxes are)
The Partnership/LLC will issue each owner a K-1 showing their share of profit/loss. Each owner is required to enter that K-1 on their personal 1040 tax return. If you file a joint personal 1040 return, there would be a separate K-1 entered into that return for each of you.
If only one of you owns an LLC, that's a single member LLC that gets reported on SCH C. If you elect to file separate returns, then it only gets reported on the tax return of the owner of the business. Nothing is split. Understand that when a married couple files separate returns, you "both" automatically disqualify for a number of deductions and credits you would otherwise get if you filed joint.
