Personally I would just pay up and be done with it since you have been doing some unorthodox things (you cannot just flip flop who will claim LLC income belonging to you to others and back if you don't do it correctly) and you probably did not keep a separate business bank account so when you gave them access to your personal bank account they determined that ALL deposits to that account was considered business income including the amount your OTHER gives you. You may be able to fight this but at this point I believe it will have to be in court if they have made a final determination which means you need a tax attorney ASAP. Read the notice they sent you carefully then make a decision or seek professional assistance.
