What is worth reusing
An earlier filing holds decisions. Someone chose a concept for each line, someone decided which dimension members applied, and someone created extension elements where the standard taxonomy had nothing that fit. Those decisions took time and judgment, and the same registrant describing the same business will usually want most of them again.
- Concept choices for lines that have not changed in nature, such as revenue, cash and ordinary operating expenses.
- Dimension members for stable breakdowns, such as segments and product lines.
- Extension elements the registrant created, along with the reasons for them.
- The structure of the tables: which rows exist, in which order, and what the totals are.
Equally, be clear about what is not worth reusing. Values change every period. Narrative changes. Anything tied to a date has moved. Treat a reused tag as a good starting guess and not as a settled answer: it is correct only while the line item, the accounting and the taxonomy are what they were.
Reuse matters for a second reason. A full set of financial statements must show the earlier periods alongside the current one.
Presenting only partial face financial statements is not permitted, such as by excluding comparative financial information for earlier periods.
An earlier filing is therefore not only a source of tags but also the source of the comparative figures, which must appear and must be tagged consistently with the current ones.
Check the taxonomy first
Before reusing a single tag, ask whether the taxonomy has changed since the earlier filing. A tag is a pointer into a particular version of a taxonomy, and the pointer is only as good as the version.
The set of standard taxonomies EDGAR accepts changes periodically, as new taxonomies and new versions are added and obsolete ones are removed.
In practice this means three checks. Confirm which version the earlier filing used and which one the current filing will use. Look for concepts that were renamed, replaced or removed between the two, because a tag that pointed at a concept that no longer exists cannot simply be copied. And look at each extension element again: if the standard taxonomy has since added a concept that fits, the extension is no longer needed, and keeping it makes the filing harder to compare with others.
Do this check once, up front, for the whole filing. It is far cheaper than finding a dozen retired concepts one validation message at a time.
Bring in the prior filing
To reuse an earlier filing you first need it in a form you can work with: the tagged document as it was filed, and the extension taxonomy that came with it. Start from the version that was actually filed, not from the working draft that preceded it, because the two differ whenever a late change was made.
- Identify the filing precisely: the registrant, the form, the period and the date it was filed.
- Bring in the document together with its extension taxonomy. A filing without its extension elements will show concepts that nothing defines.
- Check that it arrived whole. Compare the count of facts and the list of sections with what you expect, and open a few facts from the beginning, the middle and the end.
- Note its source. Anyone who later asks why a line is tagged a certain way should be able to follow the answer back to a named filing.
A registrant that has never filed in this format has nothing to bring in, and its first filing is a fresh set of decisions. Plan more time for it, and treat that filing as the one that every later filing will reuse.
Compare concept by concept
A line-by-line comparison of two documents is a poor tool here, because text moves and wording changes while the tags beneath it do not. Compare instead by concept: for each concept in the earlier filing, find it in the current draft, and set the two values side by side.
Each concept falls into one of a few groups, and each group has its own question.
- Changed value. This is the normal case. Ask only whether the size of the change is plausible.
- Unchanged value. Ask whether it is really unchanged, or whether a number was left in place from the last filing and not updated.
- Removed. A concept that was in the earlier filing and is missing now means a row was deleted, a line was retagged, or something that should be there is missing.
- Added. A concept that is new needs a fresh decision, since nothing from the earlier filing can answer it.
| Concept | Earlier | Current | Question |
|---|---|---|---|
| Revenues | 1,000 | 1,100 | Is the change plausible? |
| Operating lease liability | 250 | 250 | Is it really unchanged? |
| Restructuring charges | 40 | None | Deleted, retagged or missing? |
| Goodwill impairment | None | 30 | What concept fits? |
The comparison does not decide anything. It points a reviewer at the places that need a decision and lets the rest go by. Done once per filing, it is the quickest way to find what changed that nobody mentioned.
Check every reused tag
A tag that was right last time can be wrong now, and nothing in the document will say so. Reused tags need a deliberate second look, and the more mechanical the reuse, the more important the look.
- Does the line mean the same thing? A caption that did not change can still describe a different item if the underlying accounting did, as when a new standard changes how a balance is built.
- Do the dimension members still apply? A new segment, a renamed product line or a discontinued business changes the members, and a row may need a new one.
- Are the sign and scale the same? A table that was reformatted can keep its concept and change its sign convention.
- Is the concept still the best fit? A new standard concept may now describe the line better than the one chosen last time.
- Is the extension still justified? See the taxonomy check above.
Make the reused tags visible to reviewers, so that a reviewer can tell a tag that was reused from one that was chosen fresh, and can give the first kind a proportionate but real check. Do not accept a batch of reused tags on the strength of the batch. Read the exceptions in full, and sample the rest.
The failure to guard against is quiet. A reused tag that is wrong still validates, still renders and still looks like its neighbors. Only a person who asks the question will find it.
New periods, new contexts
Tags carry over from one filing to the next, but contexts do not. Every fact sits in a context that names a period, so every period in the new filing needs its own, built from the dates of the new filing and not copied from the old one.
- The dates move. Last year’s current period is this year’s comparative, and this year’s current period is new. Check both ends of every duration and the single date of every balance.
- The comparative column changes its role, not its facts. The figures in it should match what the earlier filing reported for that period, unless a restatement says otherwise, and any difference should be explained.
- Fiscal calendars matter. A registrant whose year ends on a fixed weekday has start and end dates that shift from year to year, so check them against its fiscal calendar and not against the previous filing.
- A quarterly report differs from an annual one. Take care when reusing tags from a filing of another kind, because the periods it reports, and the comparatives it needs, are not the same.
Finish with a read of the comparative figures against the earlier filing, line by line, and then validate. A filing that reuses well is one where the tags are familiar, the contexts are new, and a person has checked the join between them.
How Disclose IQ approaches it
- Bring in an existing iXBRL filing and compare a draft with it, concept by concept.
- Match each untagged figure to the prior filing's tag, see why, and accept it.
- The prior filing can be one tagged on the platform or one you imported.
- Nothing is tagged until a person accepts it, and each accepted tag records where it came from.
General information, not legal advice. Read the current form and rules.