The change won't affect you reporting requirements. You will still have to file 1020S federal tax return and applicable states' returns, if any. The only difference, you'll issue one K-1 instead of two.

There are a couple of items to keep in mind:

• You will need to make sure that the one shareholder's K-1 is marked final
• Only current year distributions are reflected on the K-1
• If the former shareholder received any liquidating distributions, those must be reported on a form 1099-DIV in box 9 or 10 as applicable.
• If the S corporation "redeemed" the one shareholder, then you will need to reduce the AAA by the applicable ownership percentage of the former shareholder if the redemption qualified as a sale or exchange.  Based on the limited facts, it appears that it does qualify since the former shareholder completely terminated their ownership.