Not really, people also pay tax on profit not revenue. Expenses related to business activity can generally be deducted in most places no matter whether you are incorporated or not. It's the basis on which business expenses you claim back from your employer are not taxed and the way unincorporated sole traders and bare partnerships are usually taxed. The rules on what types of expenses are tax deductible are pretty similar. If you incur business expenses which are not repaid by your employer you can usually reclaim tax on them.