If I own 2 businesses, with one making $5,000 profit? -

and the other loses $4,000, then do I owe the IRS 15% self-employment taxes on the $5,000 profit, or just on $1,000 combined profit?

we own 7 different factories under 3 different company names.. all which are indepenant of each other even though we share one large office for all 3 as a headquarters .. we used to be able to right the loss from one off against another several years ago but now the laws have been changed and all the companies have to be seperate enties .. we cannot even transfer money from one to the other to help out in rough times .. any company trying to do this any more is asking for trouble with the irs ..keep them seperate