1. A computer-implemented method for categorizing documents, comprising: receiving, at a computer system, topic information for a source document, the information including at least one topic and a weight for each topic, where the topic relates to content of the source document, and the weight represents how strongly the topic is associated with the source document; generating similarity scores based on a weight of each topic in the source document and the weight of the same topic in each document within one or more sets of documents, where each document in the one or more sets of documents comprises topic information; generating, based on the similarity scores, a confidence score for each of the document sets with respect to the source document; comparing the confidence score for each of the document sets to a threshold confidence score; categorizing the document sets into classes based on the comparison of confidence scores for each of the document sets; selecting one or more of the classes of document sets; determining one or more filing attributes for the source document based on the selected one or more classes of document sets; and outputting the filing attributes.