A method for processing document data in a document data processing system that comprises at least one document generation computer (3, 12), a processing computer, an electronic document output system (6, 6a..6d, 22a, 22b, 81) and a monitoring computer, wherein - document data are generated on the document generation computer (3, 12) by means of a document generation module, - the document data are transmitted from the document generation computer (3, 12) to the processing computer and are processed there, and - the processed document data are forwarded to the document output system (6, 6a..6d, 22a, 22b, 81) for the output of the documents, wherein the document output system (6, 6a..6d, 22a, 22b, 81) buffers the received document data and/or outputs them directly to one or more printing devices (6, 6a..6d), wherein - in the processing computer for optimizing the control of the subsequent document output by means of a processing module -- control data are added to the transmitted document data (49, 85a, 86a), by means of which the subsequent procedures or output devices can be monitored and/or controlled, or -- control data which are not required for the further processing of the document data are removed from the transmitted document data (49, 85a, 86a), - a control buffer file for the added control data and a document buffer file for the document data are automatically formed and stored by a control service program running on the processing computer so that the document data can again be provided by the processing computer in the case of an error in the document output system (6, 6a..6d, 22a, 22b, 81) and can be fed to the document output system (6, 6a..6d, 22a, 22b, 81), and - the document output system (6, 6a..6d, 22a, 22b, 81) is monitored with the control data by the monitoring computer under real-time conditions in that errors in the further processing of the document data can be determined, and, as soon as an error is determined by the monitoring computer, the monitoring computer can give feedback to the processing computer. - document data are generated on the document generation computer (3, 12) by means of a document generation module, - the document data are transmitted from the document generation computer (3, 12) to the processing computer and are processed there, and - the processed document data are forwarded to the document output system (6, 6a..6d, 22a, 22b, 81) for the output of the documents, - in the processing computer for optimizing the control of the subsequent document output by means of a processing module -- control data are added to the transmitted document data (49, 85a, 86a), by means of which the subsequent procedures or output devices can be monitored and/or controlled, or -- control data which are not required for the further processing of the document data are removed from the transmitted document data (49, 85a, 86a), -- control data are added to the transmitted document data (49, 85a, 86a), by means of which the subsequent procedures or output devices can be monitored and/or controlled, or -- control data which are not required for the further processing of the document data are removed from the transmitted document data (49, 85a, 86a), - a control buffer file for the added control data and a document buffer file for the document data are automatically formed and stored by a control service program running on the processing computer so that the document data can again be provided by the processing computer in the case of an error in the document output system (6, 6a..6d, 22a, 22b, 81) and can be fed to the document output system (6, 6a..6d, 22a, 22b, 81), and - the document output system (6, 6a..6d, 22a, 22b, 81) is monitored with the control data by the monitoring computer under real-time conditions in that errors in the further processing of the document data can be determined,