The Cologne archdiocese has been under pressure to divulge more of its finances since Pope Francis removed a bishop in Limburg, near Frankfurt, last year for spending over £20 million from secret funds on a new luxury residence.
According to Reuters, documents posted on its website on Wednesday show Cologne had assets of £2.5bn at the end of 2013.
Announcing their report on Ash Wednesday, the start of the Lenten period of self-denial and reflection, Cologne church officials stressed the extensive holdings helped care for 2 million Catholics, 60,000 staff and 1,200 churches and chapels.
"The archdiocese doesn't sell products or earn profits from its services, so it has to finance itself mostly from its assets," said financial director Hermann Schon.
Germany's Catholic and Protestant churches benefit from a church tax imposed on all their members. The report said Cologne reaped over £422 million pounds from the tax in 2013 and spent over half of that on pastoral and charity work.
German dioceses had traditionally published their annual operating budgets, but not a full balance sheet.