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Roll forward in iXBRL Explained

XBRL statements are being prepared by companies once every quarter or every year depending on the regulatory requirements of each country. Updating an XBRL document for a new period requires four types of changes to be managed:
1. Changes in the columns of data being disclosed (Month to date, Quarter to date etc)
2. Changes in the rows of data being disclosed (new line items, etc)
3. Changes to taxonomy
4. Removal of extensions to taxonomy because of changes in taxonomy

A good XBRL preparation mechanism should incorporate a “roll forward” feature whereby a past financial statement (with its foot notes) could be used to create a template for the new period preserving as much of the data as is possible/necessary so that preparation for the new period is quick and easy.

The Roll forward feature enables carrying forward taxonomy elements used in the past period to represent current period tags.The benefits of roll forward in XBRL tagging are:

a. It ensures the consistency of tags used during the previous and the current XBRL filing period
b. Provides the users with the option of retaining previous period tags, or re-tagging financial facts against different taxonomy elements for the current period

Implementing roll forward calls for in depth knowledge of the taxonomy. When taxonomy changes take place, the roll forward process should ensure that:

a. Taxonomy elements used in previous period are retained to tag the corresponding facts for the current period.
b. Certain previous period elements are replaced with more appropriate taxonomy elements for current period.
Example: The current period fact is tagged with a child concept compared to the previous period where it was tagged with a higher-level concept, say, parent element. This change might happen due to additional disclosure provided in the financial report.
c. Additional taxonomy elements are tagged against new facts found in the current period source document.
d. Deprecated element tags (elements removed in the new taxonomy) from previous period are removed from the current period tags and relevant current year taxonomy elements are used.

Implementing roll forward in a tagging tool calls for expertise in two areas: accounting standards and software development. DataTracks’ iXBRL software supports the roll forward feature. When an entity or accounting firm outsources its iXBRL conversion, DataTracks will ensure that:

a. Current period and previous period facts are tagged to the same element, for cases where previous period filing was done in iXBRL
b. Customers are informed of any changes in tagging decisions that overrides previous period tags.
c. For first time iXBRL filers, current period facts alone are tagged

Customers can benefit from the roll forward process by providing DataTracks with the instance document of the previous year. If customers have used DataTracks services for previous period, DataTracks would automatically apply the roll forward procedure using their previous period file.

DataTracks UK is a leading provider of XBRL services to Accounting Firms and Businesses. DataTracks ( provides iXBRL Managed Tagging Services to help companies convert their financial statements and tax computations to iXBRL format for filing with HMRC. All DataTracks services are provided through an easy to use e-commerce portal. User can register, create entities, place orders, pay, upload files and download iXBRL output when ready. DataTracks developed its XBRL conversion software in-house, and was designed to support roll forward. As a result, clients are assured of consistency in tagging to their iXBRL documents and conforming to the latest taxonomy.

To find out more about DataTracks, visit or send an email to

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