There are “storage partitions” (if I’m remembering the wording correctly) that let you put documents into physical storage locations, but there’s not a formal folder structure. For me I constantly found myself needing documents in two places (eg: property tax bill in both the folder for my house as well as my annual income tax filing, since I want all the documents for that together too). Formal folder structure was too limiting for me. Having things tagged just works better for me and eliminated my problem of having to commit to a folder structure that I wouldn’t like next year.