The probe, which the DFB said was unrelated to any of its own activities, was focusing on revenues and taxes paid by some referees.
DFB General Secretary Wolfgang Niersbach said he would support the investigation.
"There are no allegations against the DFB," he said in a statement. "We will support the tax officers with all possible means. The correct taxation of the referee's revenues rests with the referees themselves."
The DFB said the officers were going through refereeing documents.
"The reason for this action is that according to the tax officers some referees have in the past not correctly paid taxes for their revenues."
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