If you file with the SEC, XBRL filing requirements mean you must submit financial statements, cover pages, and certain other disclosures in Inline XBRL, a format that embeds machine-readable tags inside your human-readable HTML document. Rule 405 of Regulation S-T is the governing rule, and it applies to nearly every reporting entity: domestic operating companies of all sizes, foreign private issuers, investment funds, and broker-dealers. Miss a tagging requirement or submit bad structured data and EDGAR can suspend the filing, so the technical details matter as much as the deadlines.
Who Has to File in XBRL
There is no size-based exemption. Every domestic public company must file its financial statements in Inline XBRL, whether it is a large accelerated filer, an accelerated filer, or a non-accelerated filer.1eCFR. 17 CFR 240.12b-2 – Definitions Once you are a reporting entity, the obligation attaches.
Foreign private issuers filing annual reports on Form 20-F or Form 40-F must also submit tagged financial data, whether they report under U.S. GAAP or IFRS.2U.S. Securities and Exchange Commission. Inline XBRL Investment companies, including open-end mutual funds and ETFs, face parallel tagging obligations for risk/return summary information on Form N-1A and related forms.3U.S. Securities and Exchange Commission. Open-End Management Investment Company Inline XBRL Filing of Tagged Data Broker-dealers and security-based swap dealers submit structured data under separate Exchange Act rules referenced in Rule 405.4eCFR. 17 CFR 232.405 – Interactive Data File Submissions
Which Forms and Sections Require Tagging
The core filings are the ones investors read most: Form 10-K and Form 10-Q for domestic filers, and Form 20-F and Form 40-F for foreign private issuers. In an annual report, tagging covers the cover page, financial statements, footnotes, schedules, and auditor information.2U.S. Securities and Exchange Commission. Inline XBRL
Registration statements under the Securities Act also require Inline XBRL financial data, with one exception worth knowing: initial public offering registration statements are excluded. A company going through its first public offering does not have to include tagged data in that registration statement.2U.S. Securities and Exchange Commission. Inline XBRL
Every Form 8-K requires Inline XBRL tagging of the cover page, regardless of what the filing reports. The SEC has confirmed that the cover-page requirement applies to all 8-K filings, not just those containing financial data.5U.S. Securities and Exchange Commission. Inline XBRL – Question 101.03 That catches filers off guard when the 8-K reports a purely narrative event.
Pay Versus Performance Disclosures
Proxy and information statements that contain pay versus performance disclosures have their own tagging rules. Registrants must separately tag each value in the pay versus performance table, block-text tag the footnote and relationship disclosures, and (for companies that are not smaller reporting companies) tag the tabular list of important financial performance measures.6U.S. Securities and Exchange Commission. Pay Versus Performance These tags come from the Executive Compensation Disclosure taxonomy rather than the standard GAAP taxonomy. Smaller reporting companies get a transition period and only need to provide the Inline XBRL data starting with their third filing that contains pay versus performance disclosure.
What Gets Tagged Inside the Filing
Rule 405 requires two levels of tagging, and they apply to different parts of your financial statements.
Block Tagging
Block tagging wraps an entire section of text in a single tag. For financial statement footnotes, you need block-text tags for each complete footnote, each significant accounting policy within the accounting policies footnote, and each table within each footnote.7Securities and Exchange Commission. EDGAR XBRL Guide The tagged content is captured as an XHTML fragment, so formatting like tables and bold text is preserved.
Detail Tagging
Detail tagging goes further. Within each footnote, every individual monetary value, percentage, and number must be tagged separately.7Securities and Exchange Commission. EDGAR XBRL Guide If a debt footnote says the company issued $500 million in notes at 4.5% interest maturing in 2035, each of those three data points needs its own tag. Narrative disclosures within footnotes may be tagged separately at the filer’s discretion; that is optional. The primary financial statements (balance sheet, income statement, cash flow statement, and statement of equity) require full detail tagging of every line item.
Which Taxonomy to Use
Every XBRL tag maps to an element in a standardized taxonomy, which acts as a dictionary of financial concepts. Domestic filers use the U.S. GAAP Financial Reporting Taxonomy, updated annually by FASB; the current version is the 2026 taxonomy.8FASB. FASB Taxonomies Foreign private issuers reporting under IFRS use the IFRS Taxonomy. Filers must use the taxonomy version that corresponds to their reporting period.
The Inline XBRL format itself embeds the machine-readable tags directly into the HTML document, so a single filing serves both human and machine readers instead of requiring separate files that could fall out of sync.9Securities and Exchange Commission. Inline XBRL Filing of Tagged Data
Custom Extensions
When the standard taxonomy has no element that captures a company-specific concept, you may create a custom extension, but the EDGAR Filer Manual sets tight limits. Create a custom element only if no standard taxonomy element is specific enough. Create a custom member for an axis only when no existing member adequately distinguishes the reported facts.7Securities and Exchange Commission. EDGAR XBRL Guide
Some custom elements are prohibited outright. You cannot create custom arc role declarations, custom tuple concepts, custom fraction types, or custom typed dimensions. You should not create “Total” domain members either, because the default member of an explicit axis already serves that role.7Securities and Exchange Commission. EDGAR XBRL Guide Overusing extensions is a common quality problem, since each custom element reduces how well your data compares against other filers.
Submitting Through EDGAR
Preparing the filing starts with mapping every financial fact to a taxonomy element. Each tagged value carries metadata: the entity’s CIK number, the reporting period, and the correct unit type such as U.S. dollars, shares, or percentages.7Securities and Exchange Commission. EDGAR XBRL Guide Period dates trip filers up often, particularly for non-calendar fiscal years.
You then upload the filing through EDGAR.10U.S. Securities and Exchange Commission. Submit Filings The system runs automated validation on the structured data before processing. If it finds errors, it sends a suspense notification to the email address on your company contact record rather than accepting the filing. Accepted filings receive an acceptance message and are usually disseminated to the public shortly after.11U.S. Securities and Exchange Commission. Determine the Status of My Filing
Timing counts. A live submission that begins transmitting at or before 5:30 p.m. ET on a business day and is accepted by EDGAR receives that day’s filing date. Submissions transmitted after 5:30 p.m. ET generally receive a filing date of 6:00 a.m. ET the next business day, with limited exceptions for form types like insider trading reports on Forms 3, 4, and 5.11U.S. Securities and Exchange Commission. Determine the Status of My Filing
Data Quality Checks Before You File
Beyond EDGAR’s built-in checks, the XBRL US Data Quality Committee maintains validation rules that flag common tagging mistakes. As of March 2026 there are 185 approved DQC rules in plugin version 29.0.0.12XBRL US. Approved Validation Rules The rules catch problems like an axis paired with an inappropriate member, calculations that do not balance, and context dates that fall after the reported period ends. Running the DQC checks is not required, but most preparation software integrates them, and the specific guidance they return is easier to work from than EDGAR’s error messages.
EDGAR itself publishes a catalog of XBRL validation errors that can trigger rejections. Common ones include duplicate contexts within an instance document, use of the deprecated “precision” attribute instead of the required “decimals” attribute, and a mismatch between the fiscal year end date in the filing and the company’s CIK record.13U.S. Securities and Exchange Commission. EDGAR XBRL Validation Errors Fixing them after submission means filing an amendment.
What Tagging Errors Cost You
For years, EDGAR would issue warnings for certain structured data problems and still accept the filing. That is changing. Starting March 16, 2026, EDGAR will suspend filings that contain incorrect or incomplete structured data in filing fee exhibits rather than merely warning the filer.14U.S. Securities and Exchange Commission. EDGAR to Suspend Filings for Incorrect or Incomplete Structured Data in Filing Fee Exhibits A suspended filing does not receive a filing date until the errors are corrected and the submission is reprocessed. That can mean missing a regulatory deadline.
The policy applies to fee-bearing forms like registration statements, where filing fee data must be tagged correctly. The SEC recommends using its Fee Exhibit Preparation Tool on EDGARLink Online to test filings for errors before submitting them live. EDGAR may still issue a warning instead of a suspension in some limited cases, but filers should not count on it.
The SEC also retains authority to pursue actions against companies whose filings contain materially inaccurate tagged data. Enforcement actions targeting XBRL errors on their own have been rare, but inaccurate tagging that misrepresents financial results could compound liability in a broader securities case. For most filers the practical risk is more mundane: a suspended filing that delays a shelf offering or misses an annual report deadline.
Why Paper Is Not a Backup
Rule 201 of Regulation S-T provides a temporary hardship exemption when a filer has unanticipated technical difficulties. Under it, a company may file a paper document with Form TH within one business day of the deadline and then submit a confirming electronic copy within six business days.15eCFR. 17 CFR 232.201 – Temporary Hardship Exemption
Interactive Data Files are explicitly excluded from that exemption. The text of Rule 201 carves out Interactive Data Files by name, along with Forms 3, 4, 5, Form D, and several other submission types.15eCFR. 17 CFR 232.201 – Temporary Hardship Exemption If your XBRL tagging software fails at the last minute, you cannot fall back on paper. You have to fix the structured data and file electronically. Build enough lead time into the schedule to solve technical problems before the deadline, not after.