The 2013 'e-invoicing / e-billing 2013' report from Billentis shows that only a small percentage of the bill and invoice volume has been automated:

Source & Copyright©2013 - Billentis

Yet Billentis believe that electronic and automted invoice processes can result in savings of 60-80% compared to traditional paper-based processing. And they have found that projects typically result in a payback period of 0.5-1.5 years. The leading e-invoicing countries world-wide are Brazil, Chile and Mexico due to government encouragement, and Denmark due to obligation for suppliers to send e-invoices to the public sector.

Invoice Issuer Cost Savings
Billentis analysis of the full costs of traditional paper processes v. electronic show that are total savings of €6.40 per invoice for invoice/bill issuers:

Source & Copyright©2013 - Billentis

Billentis note that in their example they have used an average sized invoice of 1.5 pages. In most organizations, the invoices are more complex and the savings are higher. Also the indirect savings are not included, e.g. online updating of the master data direct by customers.

Invoice Recipient Cost Savings
Billentis quote an actual customer case where they found that the savings were:

Source & Copyright©2013 - Billentis

Billentis again have not included the indirect savings, such as the elimination of redundancies of the supplier master data and inconsistencies.

Billentis Report
The 133 page report is full of facts, figures and tips. It covers how to improve invoice management and supply chain efficiency, the business case for issuers and recipients, how to run a successful e-invoicing project, the market, and the future for e-invoicing plus a list of sponsoring suppliers.