State paperwork explained one box at a time. Every page is written against a specific revision of the form, names it, and links the agency's own copy — so you are never filling in last year's version from memory.
All fifty states are here. Each one was written against its own agency's pages and its own form PDFs — a form appears with a walkthrough when the document itself has been read, and where an agency does not publish a form, the page says so rather than linking somewhere it is not.
A walkthrough tells you how to complete the document. What it costs to file, who owes the tax on it and how many days you have are collected in the guides and fee tables, state by state, each number carrying a link to the agency that publishes it.