When is my Sole Proprietor Tax Return Due? ShareWhen is my Sole Proprietor Tax Return Due? Sole Proprietor tax returns are filed with the owners personal tax return on Schedule C Small Business Tax Return. These returns are due April 15th of each year. Frequently Asked Questions - Business Taxes5 Steps To Take Before You Prepare Your TaxesAre Employers Required To Report The Information That Employees Claim On Their Form W-4 To The Irs?Can I Deduct My Home Office On My Business Tax Return?How Do I Choose The Right Accounting Software For My Business?Do I Have to File Taxes If My Business Made No Money?Do I Need To Make Quarterly Estimated Tax Payments?Need An Employer Identification Number (EIN)?