In most cases, the Divorce Decree should address all of those things. If the divorce is not final when the tax return is due, filing an extension for the tax return is the best option. If the divorce is already final and it was not addressed, you may need to go back to the divorce lawyers (or to lawyers that are smart enough to have included that in the original divorce).
If the Divorce Decree does not address those items, then the income is based on each of your ownership in that activity. So if both of you own 50%, then each would report 50%. For the expenses, it would be based on the amount that each of you actually pay. If the payments came from a Joint account, the rules could vary from State to State. But again, all of this SHOULD be addressed in the Divorce Decree.
