A Series LLC is a single limited liability company that can create multiple internal divisions, called series, each holding its own assets, members, and liability shield. Delaware introduced the structure in 1996 for investment funds, and roughly 20 jurisdictions now authorize some version of it. The appeal is practical: instead of forming five separate LLCs for five rental properties, you form one Series LLC and spin up a series for each property. Each series is meant to be insulated from the debts of the others, though whether that insulation actually holds depends on how you form the entity, how you keep its records, and where you do business.
How the Structure Works
There are two layers. The master LLC is what you file with the state. It has a certificate of formation, a registered agent, and an operating agreement. Underneath it, you create individual series (sometimes called cells), and each one can hold property, sign contracts, and run a separate line of business. Delaware’s statute puts it directly: a series can have “separate rights, powers or duties with respect to specified property or obligations” and “a separate business purpose or investment objective.”1Justia Law. Delaware Code Title 6 Chapter 18 Subchapter II Section 18-215
The core promise is an internal liability firewall. If Series A owns a commercial building and gets sued over a slip-and-fall, only Series A’s assets are exposed. The property in Series B and the cash in Series C stay out of reach. That firewall exists by statute, not by default. Three conditions have to be met in essentially every state that allows the structure: the operating agreement must authorize series, the certificate of formation must carry a notice that liabilities are limited between series, and each series must keep records that account for its assets separately from every other series and from the master.1Justia Law. Delaware Code Title 6 Chapter 18 Subchapter II Section 18-215
Ownership and management can differ from one series to the next. One group of investors might hold 70% of a commercial series while a different group owns a residential series outright. One series can be member-managed while another has a designated manager. That flexibility is why the structure gets used for real estate portfolios, joint ventures, and businesses that want to isolate risk across product lines.
Protected Series and Registered Series
In several states, including Delaware and Texas, there are now two kinds of series, and the difference matters.
A protected series is the original form. You create it internally through the operating agreement, and it never files with the Secretary of State. It has statutory liability protection, but it doesn’t appear in state records as a separate entity, can’t get its own certificate of good standing, and won’t show up when a lender or counterparty searches the state’s business database.2State of Texas. Texas Business Organizations Code Section 101-601
A registered series files its own certificate, gets its own public record, and can obtain a standalone certificate of good standing. For purposes of the Uniform Commercial Code, a registered series qualifies as a registered organization, which makes secured lending cleaner. The trade-off is cost: registered series typically carry their own annual fees, and in Delaware each one owes a separate annual tax. Texas’s Business Organizations Code lays out both options so organizers can pick based on whether public recognition matters for a given unit.2State of Texas. Texas Business Organizations Code Section 101-601
What Formation Actually Requires
Formation starts with filing a certificate of formation (sometimes called articles of organization) with the Secretary of State. For a Series LLC, that document needs one addition a standard LLC doesn’t: a notice of limitation on liabilities. The notice tells the public that debts of one series can’t be enforced against the assets of another.
Under Texas law, including that notice in the certificate is enough to satisfy the statutory notice requirement, even if no series exist yet and even if the notice doesn’t use the words “protected” or “registered.”3State of Texas. Texas Business Organizations Code Section 101-604 – Notice of Limitation on Liabilities of Protected Series or Registered Series Delaware has an equivalent rule.1Justia Law. Delaware Code Title 6 Chapter 18 Subchapter II Section 18-215 Leave the notice out of the initial filing and the statutory firewall never activates. The rest of the certificate is standard: entity name with an “LLC” designation, registered agent with a physical in-state address, duration, and whether management is by members or managers.
The certificate creates the master entity. The operating agreement is where the series themselves come to life. It is also the document a court will read first if the firewall is ever challenged. A workable operating agreement covers:
- How new series are created internally without amending the public filing
- Which assets belong to each series, identified by listing, category, or a clear allocation method
- Who owns what percentage of each series and what voting and economic rights come with it
- Whether each series is independently managed or run by the master’s managers
- How financial records will be kept separately for each series
- How an individual series is dissolved without affecting the rest
Filing fees for the master entity generally run from about $100 to $300. States that offer registered series often charge a per-series fee at formation, commonly in the range of $25 to $50, and some charge separate annual fees for each registered series. Electronic filing processes in a few business days in most states; mail can take weeks.
Recordkeeping Is the Shield
The liability firewall is only as strong as the books behind it. Every state statute conditions the shield on the same point: each series’ assets must be accounted for separately from every other series and the master.
Texas law says the limited liability of a series applies “only to the extent the records maintained for that particular series account for the assets associated with that series separately,” and allows identification by specific listing, category, type, quantity, percentage, or “any other method in which the identity of the assets can be objectively determined.”3State of Texas. Texas Business Organizations Code Section 101-604 – Notice of Limitation on Liabilities of Protected Series or Registered Series Delaware uses nearly identical language.1Justia Law. Delaware Code Title 6 Chapter 18 Subchapter II Section 18-215
Separate bank accounts for each series aren’t explicitly required by most statutes, but they’re the simplest way to show financial separation. If every series’ cash moves through one account, you are asking a court to trust an internal ledger. Separate accounts make the separation obvious. At minimum, keep separate books and financial statements for each series, track income and expenses independently, and don’t move money between series without documenting the transfer as a loan or contribution with clear terms.
Sloppy records don’t just weaken one series. If a court finds assets were routinely commingled with no meaningful tracking, it can treat the whole structure as a single entity for liability purposes. The internal firewall disappears, and every series’ assets become fair game for any creditor.
Federal Tax Treatment
The IRS has never issued final regulations on how Series LLCs should be classified. In 2010, it published proposed regulations stating that each domestic series should generally be treated as a separate entity formed under local law.4Federal Register. Series LLCs and Cell Companies Under that framework, each series would be independently classified (disregarded entity, partnership, or corporation) using the same check-the-box rules as any other LLC.
Those proposed regulations were never finalized. In practice, most tax advisors treat each series as a separate entity, so a series with more than one member is a partnership unless it elects corporate treatment, and a single-member series is a disregarded entity. Whether a series needs its own EIN depends on how it is classified: a disregarded entity owned by an individual generally uses the owner’s Social Security number, while a series taxed as a partnership needs its own EIN. Because the regulations aren’t final, work with a tax professional who has specific Series LLC experience, especially if series have different ownership structures or you operate in multiple states.
Where You Can Form One, and the Cross-State Problem
Roughly 20 jurisdictions authorize Series LLCs. Delaware’s statute at 6 Del. C. ยง 18-215 is the most developed framework.1Justia Law. Delaware Code Title 6 Chapter 18 Subchapter II Section 18-215 Texas provides detailed treatment of both protected and registered series.2State of Texas. Texas Business Organizations Code Section 101-601 Other states with enabling statutes include Illinois, Nevada, Wyoming, Alabama, Indiana, Iowa, Kansas, Missouri, Montana, Nebraska, North Dakota, Oklahoma, Tennessee, Utah, Virginia, and the District of Columbia.
Nevada requires three things for a valid series: articles of organization that authorize series, an operating agreement defining each series’ rights and duties, and records that account for each series’ assets and liabilities separately.5Nevada Legislature. NRS Chapter 86 – Limited-Liability Companies Wyoming takes a similar approach, letting the operating agreement establish designated series of members, managers, transferable interests, or assets.6Justia Law. Wyoming Statutes 17-29-211 – Series of Members, Managers, Transferable Interests or Assets The Uniform Law Commission approved the Uniform Protected Series Act in 2017 to standardize treatment, but adoption has been gradual and the statutes still differ meaningfully from state to state.
The harder issue is what happens when a Series LLC does business in a state that has no series statute, which is more than half the country. There is no uniform answer. Some states register only the master entity and treat the series as part of it. Florida requires each series to apply separately for a certificate of authority. Others have no formal policy. Case law is thin; few courts have squarely ruled on whether a non-series state must honor the internal liability shields of a foreign Series LLC.
Practitioners generally point to two principles when predicting outcomes: interstate comity, under which states respect one another’s legal structures, and the internal affairs doctrine, which holds that the law of the state of formation governs an entity’s internal organization. Neither is a guarantee. A creditor suing in a state without a series statute has a reasonable argument that local law governs whether one series’ assets can be reached for another series’ debts. If a series will own property or do significant business in a state that doesn’t recognize the structure, forming a standalone LLC there is often the safer path.
When It Fits, and When It Doesn’t
The Series LLC works well in one specific situation: multiple similar assets, each carrying moderate risk, where you want liability separation without paying to maintain a stack of standalone LLCs. Residential real estate investors who own a dozen rentals are the classic case. Each property goes into its own series, the owner pays one set of state fees for the master, and a tenant’s lawsuit against one property can’t reach the others.
The structure fits less well with high-value assets, with operations in states that lack series statutes, and with businesses that need each unit to have a clean public record for lending or regulatory reasons. A bank lending against a specific property often wants a standalone LLC on the title, not a series tucked inside another entity’s operating agreement. Registered series solve part of that problem where available, but lender acceptance is still inconsistent.
The savings over separate LLCs are real but can be overstated. You save on initial formation fees and consolidate some annual filings, but you still need separate bank accounts, separate books, and a more complex operating agreement than a plain LLC requires. With only two or three assets, the savings may not justify the extra complexity or the cross-state recognition risk that comes with the structure.