2005-10-11 Signature makes the digital invoice deed of trust

To send invoices only electronically saves time and money. Due to qualified signatures also the tax office will accept them.

Is an invoice is received digitally, then the invoice must be proven by an electronical signature as a documentary document. Only then an invoice is VAT deductible. The liability of the invoicing party is to provide the claim with a digital signature. In response to it the receiver must check the signature. The signature law of Germany will regulate the look of the signature.

Here the legislator offers different procedures as for example S/MIME (Secure/Multipurpose Internet Mail Extension) or Secure Edifact. Therefore the sender of the invoice gets from a neutral TrustCenter a reader and a smartcard, on which is saved an individual pair of keys (private and public key). In the mentioned TrustCenter are desposited the exact identity of the signer as far the public key. In return to that the invoice recipient must decode and archive the signature over a public key. Therefore the check-sum for the message will be calculated and compared with the received hash-value.

A confirmation proves the integrity of the received invoice.

The functions “sign” and “code” are effected with the signature-card. The vouchers must be archieved on both sides for 10 years and in unalterable form, for example in a secured PDF-format on a CD-ROM. Also the certificate as proof of the authenticity and intactness of the data requires archieving.
To disburd the finanicial accounting it makes sense to use holistic solutions, which process both paper-based invoices and permit an electronical signed data-exchange.
The smartcard including reader and software which are necessary for the digital signature can be ordered in the local chamber of commerce and industry and will be delivered after the personalization of the trust-center. The invoice-recipient can check with the free Acrobat Reader (from version 6), if the certificate of an invoice is valid.

The most important advantages of of such digital invoices are:
· Costs for paper, printout and and postage leave out (medium cost-reduction over up to 80%)
· Substantial time-savings
· Decreases of the costs for the registration and verification of paper-invoices
· The law-conformel signature allows to deduct the input-tax, without additional submission of paper-invoices
· Acceptable interest profits can be realized
· Full automatically archiving of electronically invoices let make a more efficient and more comfortable processing of incoming-invoices.

sources: Computerzeitung Nr. 39-2005 / Creditreform 4/05
overview about the from RegTP allowed trust-center:

• information over S/MIME in Wikipedia
• chamber of commerce and industry „Mittlerer Niederrhein“ to the subject "digital signature"
• further information to the digital signature of the chamber of commerce and industry „Mittlerer Niederrhein“
• Federal office for security in the IT-technology

(sr/ct)