Archiving of paper is expensive, as documents must be stored in a dry environment, indexed and kept in an orderly fashion to allow quick retrieval. At the end of the retention period documents are (normally) securely destroyed.
Archiving is often outsourced. If a public sector organisation processes for example 50 million invoices per annum and they are archived for 6 years, there will be a minimum of 300 million documents in storage.
Note: suppliers also have to archive the same document so the number doubles.
Electronic invoicing allows for the efficient archiving of electronic documents, recognizing the challenges and costs involved and provided it is executed in a safe and controlled way.