Can I keep my two businesses separate for tax purposes?
Your question boils down to this: How does an LLC report profits, losses, expenses, etc., from two distinct businesses both to the LLC’s members, and to the IRS?
I have to make a couple of assumptions here: One, you do not have a specific legal agreement in place that states profits will be split up any differently than the 50/50 ownership you mentioned above. Two, your businesses use the same Employer Identification Number through the LLC.
With those assumptions and from the limited information I have, here's what you need to know:
LLCs are the taxable entity here, since the businesses are both owned by the LLC they operate like separate divisions of the same company. Once each business earns profit or realizes a loss, it all rolls up to the LLC. Essentially, once the profit/loss is reported up to the LLC, it is one big pool of money and it does not matter which business earned it.
So, as a 50/50 member of the LLC you would receive 50 percent of the profits/losses for the LLC--meaning the sum total of each business. These businesses would not be considered distinct for tax purposes.
The LLC should report all profits/losses to you on Form K-1. This would include the combined profit/loss from both businesses owned by the LLC.