Given that the Staff from the SEC’s Division of Economic and Risk Analysis recently had to post this note about errors for XBRL tags on “public float” amounts, I thought I would list the ten most common XBRL errors made by filers of Form 10-Ks, based on observations from the SEC’s DERA staff, Corp Fin staff comment letters and other commentary:
1. Incorrect Tag Selection: Using an inappropriate element from the taxonomy that doesn’t accurately reflect the meaning of the disclosure. For example, tagging a non-cash item like stock-based compensation using a generic “expense” tag.
2. Use of Extended Tags (Custom Elements) When Not Necessary: Creating custom (extension) elements instead of using an available standard tag from the US GAAP taxonomy. The implication is that it reduces comparability across filers and increases the risk of tagging errors.
3. Sign Errors: Tagging amounts with the wrong positive or negative sign (e.g., reporting a loss as a gain). The common areas where this happens includes: deferred taxes, impairments, or other comprehensive income components.
4. Incorrect Period Type: Using a duration tag for an instant fact, or vice versa. For example, tagging a balance sheet item (instant) with a duration-type tag.
5. Tagging Text Blocks Incorrectly: Misapplying or omitting required text block tags for entire footnotes or disclosures.
6. Missing Required Tags: Omitting tags for required disclosures such as accounting policies, fair value disclosures, or income taxes.
7. Incorrect Units or Scales: Tagging data in thousands or millions, but not correctly reflecting that in the XBRL tags. For example, reporting $1,000,000 as “1,000” without properly indicating the unit of measure.
8. Context Reference Errors: Applying incorrect or inconsistent context references (e.g., wrong date or entity segment) to facts. The effect is that it makes data meaningless or misleading for users.
9. Inconsistent Use of Dimensions: Misapplying dimensions or axis-member combinations, or inconsistently applying them across related disclosures. For example, using different dimensions for similar items in separate schedules.
10. Validation and Calculation Errors: Failing to check for calculation inconsistencies where values should sum (e.g., subtotals not matching totals).
Authored by

Broc Romanek