Per IRS Publication 587, Business Use of Your Home, page 7:
If you rent the home you occupy and meet the requirements for business use of the home, you can deduct part of the rent you pay. To figure your deduction, multiply your rent payments by the percentage of your home used for business.
If you own your home, you cannot deduct the fair rental value of your home.
Starting in tax year 2018, you can no longer deduct expenses for using your home as an employee as a miscellaneous deduction.
If you are self-employed and file Schedule C (Form 1040):
To enter information for self-employed business use of home expenses in TaxAct:
Refer to IRS Publication 587 for additional information.