Accretion
Accretion is the ongoing addition of new records to an existing series, collection, or accession that continues to grow over time under the same provenance and disposition rules.
Accretion refers to material added to an established records series or archival collection after its initial creation or accession, because the recordkeeping activity that produced it is still active. Rather than treating each new batch as a wholly separate body of records, accretion folds incoming material into an existing aggregation that shares the same originating office, function, and disposition instructions.
It matters because retention and disposition are applied at the series level. A series defined once continues to receive accretions for as long as the underlying business process operates, so the retention schedule must anticipate growth rather than assume a fixed, closed set. Consistent provenance keeps the added material intelligible and defensible.
For example, an agency’s annual budget files form one series; each fiscal year’s records are an accretion to that series, not a new one. In archives, a periodic accretion to a donated collection is described and accessioned under the existing record group. Distinguish accretion from a true new accession, which establishes a separate, independently scheduled body of records.