Per the IRS Closing a Business Checklist website:
Closing your business can be a difficult and challenging task. The IRS has resources that can help you navigate this. On this page, you’ll find the steps you’ll need to take to close your business from a federal tax perspective regardless of your business type and information to help you take care of your employees. Whether a sole proprietorship, partnership or corporation, information on this page will help you understand what to file and how to report income you receive and expenses you incur before closure. Remember to check your state responsibilities when closing a business.
The annual tax return for a partnership (1065), corporation (1120), S corporation (1120-S), Limited Liability Company (LLC), 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 Schedules K-1, do the same for the Schedules 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.
Note. Schedules C (Form 1040), E (Form 1040), and F (Form 1040) do not have check boxes to indicate a Final Return.
Refer to the previous link for additional information.
Note that any link in the information above is updated each year automatically and will take you to the most recent version of the document at the time it is accessed.