What each document is
Articles of organization (called a certificate of formation in some states) are the public filing that creates the LLC. You submit them to the state, they list the basics - the company name, the registered agent, sometimes the members - and once accepted, the LLC legally exists. The filing is short and public.
An operating agreement is the private rulebook. It is not filed anywhere. It records who owns what percentage, how profits and losses are split, who can sign for the company, how decisions get made, and what happens when a member leaves or the company closes.
Why the private document matters more day to day
Once the state approves your articles, you will rarely look at them again. The operating agreement is the document you reach for when money moves or people disagree. A single-member LLC needs one too: banks routinely ask for it when opening a business account, and having the separation in writing supports the liability protection that is the whole point of the LLC.
What a good operating agreement covers
- Ownership percentages and what each member contributed - cash, property or work.
- How profits are distributed and when.
- Who manages the company: the members themselves or appointed managers.
- How new members join and how existing ones exit, including what happens to their share.
- What triggers dissolution and how the company winds down.
Do you legally have to have one?
Most states do not require an operating agreement to form an LLC, though a few expect one to exist. But not required is not not needed. Without one, your state's default LLC rules fill every gap, and the defaults are generic - equal profit splits regardless of contribution, for example. Rules vary by state, so check yours; the pattern is consistent: the defaults are written for nobody in particular, and your agreement is written for you.
The practical order
File the articles first - the LLC must exist before its members can agree to anything as members. Then draft the operating agreement before the money starts moving, while everyone still agrees. Changing the document later requires the same consent you would rather spend on the business.
FoundStart's formation guides walk through the filing steps state by state, and the partner services can handle the paperwork; the operating agreement is the one document worth reading line by line yourself.