Most businesses need to register with the IRS, register with state and local revenue agencies, and obtain a tax ID number or permit.
All states do not tax S corps equally. Most recognize them similarly to the federal government and tax the shareholders accordingly. However, some states (like Massachusetts) tax S corps on profits above a specified limit. Other states don’t recognize the S corp election and treat the business as a C corp with all of the tax ramifications. Some states (like New York and New Jersey) tax both the S corps profits and the shareholder’s proportional shares of the profits.
Your corporation must file the Form 2553 to elect “S” status within two months and 15 days after the beginning of the tax year or any time before the tax year for the status to be in effect.
Read more about IRS filing requirements for S Corporations.