A protected series LLC is a single limited liability company that can hold multiple internal “series,” each with its own assets, members, and liability shield, so a creditor who wins a judgment against one series can only reach that series’ property. About 22 states authorize the structure, and it is most popular with real estate investors and operators running several ventures under one roof. The shield is real, but it depends on strict record-keeping and on operating in a state that recognizes the entity.
How the Structure Is Built
You file one parent (or “master”) LLC with the state. Inside that parent, you create individual series, sometimes called cells. Each series can own property, sign contracts, borrow money, and have its own members and managers. The parent and every series are treated as legally distinct units even though they share a single formation document.
New series are typically created by amending the operating agreement. In states that require it, you also file a separate designation for each new series with the secretary of state. The operating agreement does the real work: it defines each series’ assets, management, allocations of profit and loss, and dissolution terms. A generic agreement that lumps every series together defeats the point of the structure.
What Makes a Series “Protected”
Not every series inside a series LLC gets the liability shield automatically. Protection kicks in only when specific statutory conditions are met, and two show up in nearly every state’s statute.
First, the formation filing must give notice that the LLC can establish protected series. Some states accept a general statement in the parent’s certificate of formation; others require a separate public filing for each series by name.
Second, each series’ records must account for its assets separately from the parent and from every other series. The records need to be specific enough that an outsider could tell which assets belong to which series. This is the condition owners most often overlook, and the one most likely to collapse the shield.
The Uniform Protected Series Act, drafted in 2017, treats each protected series as its own legal person that can own property, sue, and be sued in its own name, and it requires a protected series designation on file with the secretary of state.
What the Liability Shield Covers, and What Breaks It
When the statutory conditions are satisfied, debts and obligations of one series are enforceable only against that series’ own assets. A lawsuit against one series cannot reach the parent or sibling series. That is the whole value proposition.
Courts can still disregard the shield using the same veil-piercing doctrines that apply to any LLC. The most common failure is commingling: depositing one series’ rental income into another’s account, paying one series’ expenses from the parent without documentation, or failing to track which assets sit in which series. Any of these gives a court a reason to treat the whole thing as a single undifferentiated entity.
Other patterns that compromise the shield:
- Ignoring formalities, including failing to keep separate books, sign contracts in each series’ own name, or document significant transactions series by series.
- Undercapitalization, meaning forming a series without enough assets to cover its reasonably anticipated liabilities. Courts generally evaluate this at the time of formation, so topping up later may not fix it.
- Alter-ego conduct, such as treating series as interchangeable, misrepresenting ownership, or moving assets out of a series to dodge a creditor.
Strong on paper, the protection holds up in practice only when each series is run as its own operation.
When It Makes Sense Compared to Separate LLCs
Real estate investors are the heaviest users. An owner with ten rental properties can place each in its own series so a slip-and-fall at one property cannot reach equity in the other nine. Without the series structure, that would mean forming and maintaining ten separate LLCs.
Operators running multiple product lines or ventures use it the same way. A company that manufactures widgets and also runs a consulting practice can isolate each line, keeping a product liability claim from reaching consulting revenue. Intellectual property portfolios work similarly, with each patent or trademark family held in its own series.
The alternative is simply to form a separate standalone LLC for each asset or line of business. Both approaches compartmentalize liability. The difference is cost and certainty. Separate LLCs each need their own formation fee, registered agent, and annual report or franchise tax. A series LLC usually needs one of each for the parent, with new series created internally at little or no additional state cost. The trade-off is legal certainty: standalone LLCs are universally understood by courts, banks, and agencies, while series LLCs are newer and their shields have far less judicial testing. For two or three properties in a single series-friendly state, the savings are hard to beat. Across multiple states, the recognition problem below often tips the balance the other way.
Federal Tax Treatment Is Still Unsettled
Federal tax rules for series LLCs remain one of the structure’s biggest open questions. In 2010, the IRS published proposed regulations that would treat each series as a separate entity for federal income tax purposes, independently classified as a partnership, a disregarded entity, or an association taxable as a corporation.1Federal Register. Series LLCs and Cell Companies
Those regulations have never been finalized. More than fifteen years later, owners operate without definitive federal guidance. Most tax professionals advise treating each series as a separate entity and getting a separate EIN for any series with its own members, its own business purpose, and its own books. A series that doesn’t meet those criteria may be able to file under the parent’s EIN. This is an area where a tax advisor familiar with your situation earns the fee.
Interstate Recognition Is the Biggest Practical Risk
A series LLC formed in one state does not automatically receive the same liability treatment when it operates in another. Some states that don’t authorize domestic series LLCs will still recognize a foreign one that registers to do business there. Others have no statute on the question at all, leaving the shield’s enforceability genuinely uncertain.
Case law is thin. Comity suggests states should honor another state’s law, but a court that has never seen a series LLC has no local precedent and no obligation to apply the foreign statute. A creditor will argue the series should be treated as one entity, and the outcome is unpredictable.
If your assets sit in a state that authorizes series LLCs, the structure works well. If they are scattered across states with varying or nonexistent laws, the savings may not justify an untested shield. Confirm that every state where you hold assets or operate recognizes foreign series LLCs before relying on the structure.
Forming and Keeping One Compliant
Formation starts with a certificate of formation (or articles of organization) filed with the secretary of state in a series-friendly state. The filing must say the LLC can establish protected series. Some states require this language in the certificate itself; others let it live in the operating agreement, though putting it on the public record is safer.
Each series then needs clearly identified assets, a defined purpose, and separate records from day one. The ongoing discipline matters more than the formation paperwork. Each series should have its own bank account, its own bookkeeping, and its own financial statements. Contracts and invoices should name the specific series, not just the parent. When one series lends to another or transfers an asset over, document the deal as if two unrelated parties were transacting. Informal shuffling of money or property between series is exactly what invites a court to collapse the barriers.
The parent owes whatever annual report or franchise tax the formation state requires. Some states impose separate fees or filings on each series as well, which can eat into the cost advantage over separate LLCs. Check your state’s specific requirements before assuming additional series are free.
Banking and Insurance Friction
Opening bank accounts for individual series can be harder than expected. Many banks are unfamiliar with the structure and don’t have procedures for accounts tied to units that aren’t separately filed with the state. Bring the certificate of formation, the operating agreement showing the series, an EIN for the series or parent, and any state documentation proving the series is a distinct unit. Some practitioners bring a copy of the relevant state statute. If one bank can’t accommodate you, try another; commercial lenders and banks that serve real estate investors tend to be more familiar with series LLCs than retail branches.
Insurance has the same problem. Getting separate policies for each series, or structuring a single policy to clearly cover each series on its own, requires an insurer who understands the entity. The complexity around banking, insurance, and tax handling is manageable, but it is real, and underestimating it is how shields get compromised.