My wife is co-owner of a business, which is a multi member LLC(her and someone else). They don't have any employees under their payroll since they are the ones that provide the service themselves. That's where I'm wondering about them filing or paying quarterly taxes. They do not receive a percentage of the total revenue made by both, but their income is based on the services they each provide to a customer. The only thing they go 50/50 on is their expenses, such as rent, supplies, bills, etc. I'm wondering what forms they have to file during the year or annually.