Can quickbook online transaction data can be interfaced to DATEV (German Tax Program) system?

You need a workaround to do so. Contact @Fiat Lux - ASIA for details

I'd be happy to assist you with the DATEV system, Kim.

It looks like your issue is similar to one my colleague has already addressed. Please click this link to view the thread: Can QuickBooks transaction dates be interfaced with the DATEV system?

If you have any further questions or concerns about QuickBooks, feel free to reply to the thread. Take care.