Sole proprietor: Employee and profit-sharing contributions must be funded by your tax-filing deadline. If your business is incorporated: Employee contributions must be funded within 15 business days after the month in which you pay yourself. Profit-sharing contributions must be funded by your tax-filing deadline.
The deadline to establish your Single(k) plan for this year is December 31. Sign up online and sign the Adoption Agreement by no later than December 31. (You’ll receive your Adoption Agreement once you sign up.)