Form 966 tells the IRS your corporation has adopted a plan to dissolve. File it within 30 days of the date your board or members approved the dissolution, and attach a copy of the resolution or plan. It applies to corporations, including LLCs taxed as C-corps or S-corps, but not to partnerships or sole proprietorships. It is free to file, and it is one of the steps founders most often miss.
Inkle handles the state and IRS filings that close a US company properly.
Full guide
What is Business Dissolution?
