For login on https://sandbox.paydirekt.de/checkout/#/checkout in order to authorize a test transaction:

User Condition User name Password
Standard Buyer TESTGiroSolution_SDE-KaeuferSDE-Kaeufer2$
Age - Buyer under 18 TESTGiroSolution_unterAchtzehnunterAchtzehn2$
Buyer invalidated at paydirekt KaeuferGesperrtKaeuferGesperrt2$
Buyer invalidated at his bank TESTGiroSolution_SperreKBSperreKB2$

Please take into account the following test cases:

Warning regarding 2FA (two factor authentication):

2FA = Second Factor (authentication through a second channel)
Not all of the mentioned 2FA methods are usable with all of the test accounts and may lead to payment aborts. Generally, no useful test cases for merchants may be derived from these test amounts (because these processes run entirely on Paydirekt side).