Form SS-4 for a Protected Series: A Line-by-Line Walkthrough

Does a protected series file its own Form SS-4?

Yes, when it takes its own EIN. 1 form produces 1 number, so a series applying for an EIN files a form in its own name rather than being added to the master's. The master's existing EIN is unaffected.

The IRS issues 1 EIN per completed Form SS-4 and has no mechanism for adding a series to an existing number. A structure taking 3 series EINs files 3 forms, each naming a different entity on line 1 and each producing its own CP-575 letter.

The master's number never changes. Creating series 5 or series 20 inside an existing LLC leaves the master's EIN exactly where it was, because that number is attached to the registered entity rather than to the count of divisions inside it.

A protected series differs from a registered series only in what backs the name. A Delaware registered series has a state certificate; a protected series has a clause in the limited liability company agreement. The form is identical; the evidence behind line 1 is not.

Before filing, confirm the series actually needs a number. The 4 triggers are employment tax, excise tax, a separate income tax return, and a bank account in the series name. A series meeting none of them files nothing.

What goes on line 1 for a protected series?

The series legal name, verbatim from the company agreement, including any required parent-LLC prefix. This becomes the name on the CP-575, which the IRS prints once and never reprints.

Copy the name rather than retyping it from memory. Punctuation counts: LLC against L.L.C., a comma before LLC, and capitalisation all travel through to the CP-575 and then to every bank name-match afterwards. A mismatch of 1 character holds an account application for 5 to 10 business days.

Naming conventions differ by state and some are strict. Illinois requires a designated series name to contain the full name of the parent LLC, which produces long strings that get truncated by accident. Delaware registered series names follow the certificate. Texas and Nevada follow the company or operating agreement.

Line 2 is the trade name or doing-business-as, and it stays blank for most series. Entering the master's name on line 2 out of a sense that it belongs somewhere creates an association the IRS did not ask for and a bank does not expect.

If the name on line 1 is later found to be wrong, the correction runs through the IRS campus that issued the number and is proved with a 147C letter carrying the corrected name. There is no corrected CP-575, ever.

What address does a protected series use on lines 4 and 5?

Lines 4a and 4b carry the mailing address the CP-575 is sent to, and a series can use the master's address. Lines 5a and 5b carry the street address of the business, which is left blank when it matches line 4.

Use an address someone actually monitors. The CP-575 goes to the line 4a address unless a fax number is supplied on the cover sheet, and a letter that arrives at a registered agent who forwards quarterly is a letter that arrives late.

A non-US address is accepted on lines 4a and 4b without complication. Foreign owners of a US series file with a foreign mailing address routinely, and the IRS does not require a US address for the entity applying.

Registered agent addresses are a common and avoidable error. The agent's address is not automatically the right entry for either line, and using it means IRS correspondence lands with a third party rather than with the owner.

Filing Form 8822-B is how the address changes later. It updates both the mailing address and the responsible party the IRS holds against that EIN, and it is due within 60 days of a responsible-party change.

Who is the responsible party for a protected series?

A natural person who controls that series, named on line 7a with their SSN, ITIN, or the entry Foreign on line 7b. It does not have to be the same person as the master's responsible party.

The IRS requires a human being. Naming the master LLC as the responsible party for a series is the error that blocks these applications outright, and it produces a rejection rather than a request for clarification. The responsible party is the person who controls or directs the entity and its assets.

Line 7b takes the SSN or ITIN of that person, or the word Foreign where they hold neither. That single entry is what makes the fax route available to non-US owners without a passport upload, an ITIN application, or any identity document at all.

The daily cap attaches to this person rather than to the entity. The IRS issues 1 EIN per responsible party per day across every channel, so a structure taking 4 series numbers either spreads them across 4 business days or names different responsible parties where the facts genuinely support it.

Line 18 asks whether the applicant has ever received an EIN before, and a third-party designee can be named to receive the number. A filing agent named there can run applications the daily cap would otherwise stall.

How does a protected series answer lines 8a, 8b and 9a?

For itself, not for the master. Line 8a is yes, line 8b carries that series' own member count, and line 9a carries its classification, which locks for 60 months under 26 CFR 301.7701-3.

These 3 lines are the reason a paid filing exists at all, and they are the ones a series most often copies incorrectly from the master. A master taxed as a partnership with a single-member series answers line 8b as 1 on the series form and as its own count on the master's.

Line 9a follows from line 8b under the check-the-box defaults. A 1-member series is a disregarded entity, a 2-or-more-member series is a partnership filing Form 1065, and either can elect corporate treatment on Form 8832 or S corporation treatment on Form 2553.

The 60-month lock is the expensive part. Picking corporation on line 9a without a Form 8832 election already on file creates a mismatch inside the IRS system, and unwinding it costs roughly 60 days plus a fresh election. The lock runs 60 months under 26 CFR 301.7701-3.

Each series answers independently. A structure with 4 series can hold 4 different classifications, and the master's answer constrains none of them.

Source: IRS Form SS-4 and its instructions, and 26 CFR 301.7701-3, verified August 2026.

What do lines 10 through 18 ask a protected series?

Line 10 is the reason for applying, and banking purposes fits a series taking a number to open an account. Lines 11 to 17 cover dates, accounting year and activity. Line 18 is the signature, which the IRS requires in ink on the paper route.

Line 10 offers a set of reasons, and 2 of them fit most series: started new business, for a series beginning its own operations, and banking purposes, for a series taking a number specifically to open an account. Neither entry changes the classification set on 9a.

Line 11 is the date the series started, which is the date the company agreement created it rather than the date the master was formed. Line 12 is the closing month of the accounting year, and December is correct for most.

Lines 13 through 16 cover employment tax and stay blank for a series with 0 employees. A series taking a number specifically because it will run payroll completes them, and doing so sets up the Form 941 filing schedule from the first quarter.

Line 17 is the principal business activity in 1 sentence, describing what that series does rather than what the master does. Line 18 is the signature, printed name, title and daytime phone. The IRS rejects digital signatures on the paper route as of 2026, so it is signed in ink.

Which 5 errors stall a protected series application?

Naming the master on line 1, naming an entity rather than a person on line 7a, copying the master's member count to line 8b, picking corporation on 9a with no Form 8832 on file, and leaving line 18 unsigned.

Error 1 produces a valid EIN attached to the wrong entity, which is the worst outcome on the list because nothing rejects. The number arrives, the CP-575 looks correct at a glance, and the mismatch surfaces at a bank counter weeks later.

Error 2 rejects outright, and that is a mercy by comparison. The IRS requires a natural person on line 7a, and an application naming the master LLC is returned rather than processed.

Errors 3 and 4 both attack classification. A wrong member count on 8b sets the wrong default on 9a, and a corporation entry on 9a without a prior Form 8832 pulls the return back to disregarded entity or partnership under 26 CFR 301.7701-3(b)(1). Both cost roughly 60 days to unwind.

Error 5 is purely mechanical and entirely common. An unsigned Form SS-4 is not a filing, and the IRS returns it rather than holding it, so the whole timeline restarts while the form travels back and forth.

Who should pay anyone to file this?

An applicant holding an SSN or ITIN pays nobody. The IRS online assistant issues each EIN in about 15 minutes for $0. An applicant without either uses the fax route, also $0, or hands it to someone.

Price context, so the $97 is legible. The IRS charges $0 for the EIN itself and it never renews, so year 2 and every year after costs $0. Formation companies price it as an add-on: Northwest at $200 without an SSN, ZenBusiness at $99, Rocket Lawyer at $59.99, all verified July 2026. None of the 3 publishes a written filing deadline, and none reviews the SS-4 classification lines before filing. Full breakdown on LLC EIN cost.

What else do owners ask about Form SS-4 for a series?

8 questions come up most: whether a series files its own form, what name goes on line 1, who can be the responsible party, which member count applies, and how long the classification locks.