The annual tax return for a partnership, corporation, S corporation, limited liability company or trust includes check boxes near the top front page just below the entity information. For the tax year in which your business ceases to exist, check the box that indicates this tax return is a final return. If there are Schedule K-1s, repeat the same procedure on the Schedule K-1.
You will also need to file returns to report disposing of business property, reporting the exchange of like-kind property, and/or changing the form of your business.