Form 1120 s mailing address
The mailing address for the IRS Form 1120-S, U.S. Income Tax Return for an S Corporation, is:
Internal Revenue Service Attn: Form 1120-S 1111 Constitution Ave NW Washington, DC 20224-0024
You can also file your Form 1120-S electronically through the IRS's Electronic Filing System (e-file) or through a tax preparation software provider.