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):

1. Complete Form 8829, Expenses for Business Use of Your Home.
2. The calculation is then transferred to Schedule C, Line 30.

To enter information for self-employed business use of home expenses in TaxAct:

1. From within your TaxAct return (Online or Desktop) click Federal. On smaller devices, click in the upper left-hand corner, then select Federal.
2. Click Business Income to expand the category, then click Business income or loss from a sole proprietorship
3. Click +Add Schedule C to create a new copy of Schedule C, or click Review to review a copy already created
4. Continue to the screen titled Did you use your home for business purposes for this business? and click Yes
5. The program will proceed with the interview questions for you to enter the appropriate information

Refer to IRS Publication 587 for additional information.