You can’t deduct private or domestic expenses like childcare fees and clothes for your family. 

You can’t deduct expenses relating to income that is not taxable, for example, money you earn from a hobby. 

Certain expenses that are specifically non-deductible under the tax law can never be deducted. Examples are speeding fines and parking tickets.

Finally, you cannot deduct loans the business makes, and money drawn from the business by the owner.