As mentioned in prior responses, you should have been filing Form 941 each quarter for as long as you had an employee, assuming that this employee is paid via W-2. If you paid your employee as contract labor, you would have issued a 1099-MISC each year to this employee. In that case, you wouldn't be required to file Form 941. Form 941 deals specifically with employer withholding of income taxes from the employee's pay, then submitting it quarterly to the IRS.
I've filed for years as bookkeeper for my husband's sole proprietorship using the IRS form provided on their website. It is form-fillable, and can be printed, signed and mailed to the appropriate address at the IRS. I found that to be the simplest method. I'm linking Form 941, and instructions, below.
https://www.irs.gov/pub/irs-pdf/f941.pdf
https://www.irs.gov/pub/irs-pdf/i941.pdf
*** I am NOT a tax expert. I am a seasoned TurboTax user, and volunteer to provide assistance to TT users. Nothing I post is to be considered TAX ADVICE; I bear no legal liability for responses.***
