What Is an SEC Accession Number? EDGAR's Filing ID Explained

An SEC accession number is the unique identifier EDGAR assigns to a single filing the moment it accepts it, in the form 0000320193-26-000020. It looks like a long serial number, but each of its three parts means something specific, and once you can read it you can build the exact URL to a filing's documents or pull the filing itself from SecFeed without searching for it first.

What an accession number identifies

EDGAR assigns one accession number to every submission, whether it is a 10-K, a Form 4, a 13F-HR or an amendment to any of those. It identifies the submission itself, not the company: a company with ten filings on record has ten different accession numbers, one per filing, even though it has only one CIK.

This makes the accession number the primary key for a filing across every EDGAR tool and every service built on EDGAR data, including SecFeed. Search a company's filings, find the one you want, and its accession number is what you pass to pull that exact filing's contents.

How an accession number is structured

An accession number is always 20 characters written as 18 digits split by two dashes: NNNNNNNNNN-YY-NNNNNN.

Because the sequence resets per submitter per year, accession numbers are not comparable across different filers, and a smaller sequence number does not mean an earlier filing date once two different CIKs are involved.

Where to find a filing's accession number

EDGAR shows the accession number on every filing's index page and in the results of its company search and full text search tools, for free. The challenge is usually not finding one accession number but finding the right one among hundreds for an active filer, which is what structured search is for.

With SecFeed, searching /v1/filings by ticker, CIK, form type or date range returns the accession number alongside every other filing you can search for:

curl 'https://secfeedapi.com/v1/filings?query=ticker:AAPL AND formType:"10-K"&size=1' \
  -H "Authorization: Bearer YOUR_API_KEY"

{
  "total": { "value": 30, "relation": "eq" },
  "filings": [
    {
      "accessionNo": "0000320193-25-000079",
      "cik": "320193",
      "ticker": "AAPL",
      "companyName": "Apple Inc.",
      "formType": "10-K",
      "filedAt": "2025-10-31",
      "linkToTxt": "https://www.sec.gov/Archives/edgar/data/320193/0000320193-25-000079.txt",
      "linkToFilingDetails": "https://www.sec.gov/Archives/edgar/data/320193/000032019325000079/0000320193-25-000079-index.htm"
    }
  ]
}

Full details on the query syntax this endpoint accepts are at the EDGAR filing search reference.

Turning an accession number into a URL

EDGAR's own Archives server uses the accession number, with its dashes removed, as the folder name for a filing's documents. Given CIK 320193 and accession number 0000320193-25-000079, the filing's document folder is:

https://www.sec.gov/Archives/edgar/data/320193/000032019325000079/

The CIK in the URL path drops its leading zeros, while the accession number folder keeps all 18 digits, just without the dashes. The index page for the same filing adds the dashed accession number back as a filename: .../000032019325000079/0000320193-25-000079-index.htm. Getting either part wrong, a padded CIK or a dashed folder name, is the most common reason a hand built EDGAR URL returns a 404.

Pulling a filing's documents by accession number

Once you have an accession number, SecFeed's /v1/files endpoint lists every document, exhibit and XBRL file inside that specific filing, so you do not have to construct or parse the Archives folder by hand:

curl "https://secfeedapi.com/v1/files?cik=320193&accessionNo=0000320193-26-000020" \
  -H "Authorization: Bearer YOUR_API_KEY"

In Python, the same call chains naturally after a filing search, since the search result already carries the accession number you need:

from secfeed import Client

sf = Client("YOUR_API_KEY")
filing = sf.filings(query='ticker:AAPL AND formType:"10-K"', size=1)["filings"][0]
files = sf.files(cik=filing["cik"], accession_no=filing["accessionNo"])
for f in files:
    print(f["name"], f["size"])

This is also how how to download SEC filings with Python chains a search into a download, and it works the same way for any form type, not only 10-Ks.

Accession number amendments and related filings

An amendment to a filing, such as a 10-K/A or a 13F-HR/A, gets its own new accession number. It does not reuse or append to the original filing's accession number, even though EDGAR links the two together as the same company's filing history. If you are comparing an original filing to its amendment, match them by form type, CIK and filing date range rather than by any pattern in the accession number itself, since there is none.

Frequently asked questions

What does an SEC accession number look like?

Eighteen digits split into three parts by two dashes, for example 0000320193-25-000079: a ten digit CIK, a two digit year, and a six digit sequence number.

Is the CIK in an accession number always the company's own CIK?

Not always. It is the CIK of whoever submitted the filing to EDGAR. That is usually the company itself, but it can be a filing agent, a subsidiary's parent, or any other EDGAR filer account used to transmit the submission.

Can I search EDGAR by accession number?

Yes. EDGAR's full text search and company search both accept an accession number directly, and so does the EDGAR filing search API if you already have one and want that specific filing's details.

Do accession numbers increase in order over time?

Only within the same submitter's own filings in the same year. The sequence resets every year and is tracked separately for every CIK that files directly or acts as a filing agent, so two filings from different companies filed on the same day will not have adjacent accession numbers.

How is an accession number different from a CIK?

A CIK identifies a filer, a company or an individual, and stays the same across every filing that entity makes. An accession number identifies one specific filing. Read more about how CIKs, tickers and CUSIPs relate to each other in CIK, CUSIP and ticker: how SEC company identifiers fit together.