My ecxperience has been to date with cost sharing between 2 LLC's whose principals are essentially the same. One has both husband and wife as members and the opther connected company has only the husband as sole member. Unless a husband and wife can and choose to file separately at tax time the difference between ownbership of a H/W and just H is nothing as a joint return includes income from all parties. Where it can get a little sticky is when there is an outside the marriage member of the LLC (or if even one company is incorporated)
I have been through an IRS audit with one company who has loaned funds (by paying expenses) for teh second company. Maybe the agent found enough to make their quota and did not need to hammer on the intercompany transfers. And we have for 2016 tax year moving forward switched tax CPA firms so I have yet to see any proposed changes in how we address this. More concerning would be how the bank(s) view it and if it should all be personal draw and contribution. In the end, for 2 or more LLC or Sole Prop owned by same individual (individual refers to married couple filing jointly as well) the net taxable income for the 2 companies is equal to the sum of net taxable even if no funds were loaned or borrowed between the 2 companies but all funds came from outside
