--- title: "SEC Accession Numbers: What That 18-Digit Code Actually Means" type: learn slug: sec-accession-numbers-explained-what-the-18-digit-code-means canonical_url: https://13finsight.com/learn/sec-accession-numbers-explained-what-the-18-digit-code-means published_at: 2026-05-11T00:51:08.318Z updated_at: 2026-05-11T00:51:12.566Z author: Sarah Mitchell author_title: Education Editor author_url: https://13finsight.com/authors/sarah-mitchell word_count: 1025 locale: en source: 13F Insight --- # SEC Accession Numbers: What That 18-Digit Code Actually Means > Every SEC filing on EDGAR has an accession number — an 18-digit code like 0001067983-25-000123. The three segments encode the filer's CIK, the year, and the sequence number. Understanding the structure makes the SEC record navigable. If you've ever opened a 13F filing on EDGAR, looked at a Form 4 cross-reference, or chased a Schedule 13D footnote in a corporate dispute, you've seen something like this: 0001067983-25-000123. Eighteen digits. Three dash-separated segments. SEC documents call it an accession number, and it is the canonical primary key for every filing the SEC has ever received via the EDGAR electronic system. Understanding what each segment encodes makes the SEC record materially more navigable.Across this platform, accession numbers appear on filer profile pages, in 13D/G tables, in Form 4 insider records, and in research article citations. Knowing how to decode them lets you jump directly from any 13F Insight reference back to the SEC primary source.The Three SegmentsTake a worked example: 0001067983-25-000123.SegmentValueMeaning1 — Filer CIK000106798310-digit padded CIK of the filer (in this example, CIK 1067983 is Berkshire Hathaway).2 — Year25Two-digit calendar year the filer (or their filing agent) submitted the filing.3 — Sequence000123Six-digit zero-padded sequential number, unique within that filer-year.So 0001067983-25-000123 reads as: the 123rd filing submitted by Berkshire Hathaway (CIK 1067983) during calendar year 2025.What the Numbers Tell YouThe CIK (Central Index Key)CIK is the SEC's permanent identifier for any entity that has ever filed anything with EDGAR — companies, fund families, insiders, even SPAC sponsors. CIKs are assigned sequentially as entities first file, so older entities have lower CIKs. BlackRock, Inc. sits at CIK 2012383 (a relatively recent registration of a specific BlackRock entity); State Street Corp sits at CIK 93751 (registered in the 1970s).Note that CIK is the filing entity, not the subject of the filing. A 13F filed by FMR LLC about its holdings of Apple has the filer CIK (FMR LLC's, 315066) in the accession number — not Apple's. A Schedule 13D filed by an activist about a target company has the activist's filer CIK, not the target's.The YearTwo-digit year. The 2025 calendar year is 25; 2026 is 26. The year is when the filing was submitted, not when the underlying reporting period closed. A Form 4 transaction dated 2024-12-30 that was filed in early January 2025 will have 25 in its accession number despite reporting a 2024 transaction.The Sequence NumberSix-digit zero-padded, unique within filer + year. The number does not encode form type, subject company, or any other metadata — it's purely a within-filer-year counter incremented as the filer (or their filing agent / EDGAR submission service) submits each filing. So 000001 is the first filing of the year for that filer; 000123 is the 123rd; 012000 would be the 12,000th. Large brokers and dealers that file thousands of Form 4s annually can reach sequence numbers in the five-digit range.Why Accession Numbers Beat Plain URLsSEC EDGAR exposes filings via URLs like https://www.sec.gov/Archives/edgar/data/1067983/000106798325000123/... — but those URLs are constructed from the accession number components. If you have the accession number you can always construct the URL deterministically. The reverse is not true: the URL doesn't make the parts as obvious. Once you can decode accession numbers, you can:Jump directly from a 13F Insight article citation back to the SEC primary source using only the printed accession code.Cross-reference filings across the SEC's full-text search (efts.sec.gov) — accession numbers are first-class identifiers.De-duplicate filings programmatically — two filings with the same accession number are the same filing, full stop.Trace amendment chains — Form 13F-HR/A amendments reference the original 13F-HR by accession number in their cover page.Common Accession-Number PatternsOnce you've decoded a few hundred accession numbers, certain filers' patterns become familiar:Filing agents — Many smaller filers use third-party filing agents (Computershare, Toppan Merrill, etc.). Those agents have their own CIKs and their own sequence-number streams. An accession number starting with a filing agent's CIK doesn't tell you which underlying issuer the filing concerns — you have to open the filing to see.Very high sequence numbers — Filers in the 10,000+ range typically include the SEC's largest broker-dealer entities, the largest banks, and a handful of mass-Form-4 filing complexes. Citadel Securities, Susquehanna, and the major prime brokers all sit in this range.Year-over-year continuity — A filer's sequence number resets each calendar year. A drop in volume year-over-year (from 000800 at year-end 2024 to 000200 at year-end 2025) can indicate organizational change, M&A activity, or a regulatory filing reduction.Special CasesPaper FilingsPre-EDGAR (before 1993 broadly) and a small set of post-EDGAR paper filings do not have accession numbers in the modern 18-digit format. Some carry legacy paper-filing identifiers. Most analyses on this platform do not surface those because pre-1993 institutional ownership data is not publicly retrievable from EDGAR.Withdrawn FilingsA filing can be withdrawn (Form 25 for delisting, Form 15 for deregistration). The original accession number persists in the record; the withdrawal is a separate accession number that references the original.EDGAR OutagesThe SEC has had a small number of EDGAR outages over the years (notably in late 2023). Filings submitted during outages may receive non-standard sequence numbers or backdated accession numbers. These are rare and documented in SEC public statements.Worked Example — Following the Vanguard ReshuffleThe recent Vanguard reporting-entity reshuffle referenced three specific accession numbers:0002100119-26-000520 — VANGUARD CAPITAL MANAGEMENT LLC (CIK 2100119), filed in 2026, sequence 520. This is the 520th filing submitted by Vanguard Capital Management LLC during calendar 2026.0000102909-26-001322 — VANGUARD GROUP INC. (CIK 102909), filed in 2026, sequence 1322. The 1322nd filing — a much higher sequence reflecting Vanguard Group Inc.'s decades-long filing history and the many fund-level reportings made under that entity.0000093751-25-000602 — STATE STREET CORP (CIK 93751), filed in 2025, sequence 602.Each of those is reconstructable into a direct EDGAR URL. The leading-zero padding on the CIK and sequence components is what makes them lexicographically sortable — important for any system that sorts filings chronologically inside a single filer.Quick ReferenceCode PatternWhat It MeansNNNNNNNNNN-YY-NNNNNNModern 18-digit format: filer CIK, year, sequence0000093751-25-000602State Street (CIK 93751), filed 2025, sequence 6020001067983-25-000123Filer CIK 1067983 (Berkshire Hathaway), filed 2025, sequence 123Leading zerosPadding to fixed 10-digit CIK and 6-digit sequenceFor more on the SEC filing types that produce these accession numbers (13F-HR, 13F-HR/A, Schedule 13D, Schedule 13G, Form 4, Form 5, Form 8-K, Form 10-Q, Form 10-K), see the 13F Insight learn library. To trace a specific accession number to its source, the SEC filings hub resolves the cross-references automatically. ## FAQ ### What is an SEC accession number? An SEC accession number is an 18-digit code assigned to every filing submitted via the EDGAR electronic system. The format is NNNNNNNNNN-YY-NNNNNN: 10-digit filer CIK, two-digit calendar year of submission, and six-digit zero-padded sequence number unique within that filer-year. It is the canonical primary key for any SEC filing. ### How do I read an accession number like 0001067983-25-000123? Split it into three segments. 0001067983 is the filer's CIK (Central Index Key), padded to 10 digits. 25 is the two-digit calendar year of submission (2025). 000123 is the within-filer-year sequence number (the 123rd filing submitted by that filer in 2025). Together: the 123rd filing submitted by CIK 1067983 in 2025. ### Is the CIK in the accession number the filer or the subject of the filing? It is the filer, not the subject. A 13F filed by FMR LLC about its holdings of Apple uses FMR LLC's CIK (315066) in the accession number, not Apple's. A Schedule 13D filed by an activist about a target company uses the activist's filer CIK, not the target company's CIK. To find the subject, you have to open the filing itself. ### What does the year in an accession number refer to? The year in an accession number refers to when the filing was submitted to EDGAR, not when the underlying reporting period ended. A Form 4 for a December 30, 2024 transaction filed in early January 2025 carries 25 in its accession number even though the reported transaction is in calendar 2024. ### Why do accession numbers have leading zeros? Both the CIK segment (10 digits) and the sequence segment (6 digits) are zero-padded to fixed widths. The padding makes accession numbers lexicographically sortable, so a list of filings sorted alphabetically by accession number is also sorted chronologically within a single filer-year. The format also keeps numerical-string parsing trivial across SEC systems. ### Can two SEC filings have the same accession number? No. Accession numbers are unique across all of EDGAR — any two filings with the same accession number are the same filing. This makes accession numbers reliable primary keys for programmatic deduplication, cross-system reconciliation, and amendment tracking. Form 13F-HR/A amendments reference the original 13F-HR by its accession number in their cover page. --- Source: 13F Insight — https://13finsight.com/learn/sec-accession-numbers-explained-what-the-18-digit-code-means Author: Sarah Mitchell — https://13finsight.com/authors/sarah-mitchell Last updated: 2026-05-11T00:51:12.566Z