How can I prove self-financing of subsistence expenses?

Generally an amount of about € 45 per person and day of stay if asked for.

This amount you may substantiate by:

 - Proof of you own income

 - And by presentation of your credit card together with the accounts of the past six (6) months

Or

 - Presentation of your bank statemenrts for the past six (6) months together with a confirmation of the bank to the account.

Proof of self-financing