[Edited 02/15/17]
To enter home office deductions as an employee in TurboTax Deluxe Online:
1. Go to "Federal Taxes" at the top of the page
2. Go to the "Deductions & Credits" sub-tab
3. Navigate to "Employment Expenses"
4. Select "Start", next to "Job-Related Expenses"
5. Continue to enter your home office information and answer the questions
6. Continue until finished
Job-related
Expenses