Having a business does not make all your expenditures automatically tax deductible.

For an expense to be tax deductible it must be directly related to the operation of your business. It also must also meet the following requirements to be tax deductible it must be BOTH “ordinary” and “necessary” to the business.
“Ordinary” means that the expense is common and accepted in your type of business.

For example, if you run a bakery, it’s ordinary to buy flour and sugar as ingredients for your baked goods, along with pots, pans, ovens, and even other cooking equipment.
“Necessary” means that the expense is helpful and appropriate for your business.

For example, a baker cannot bake without flour and sugar and other ingredients. Those things, along with items, are necessary to running a bakery.

Expenses must also be directly related to your business. That means it must be something you bought to help you run your business; not something personal like a vacation or a new TV.

What is ordinary and necessary for one type of business may not be ordinary and necessary for another.  For example, while boat and fishing equipment may be ordinary and necessary for a fishing charter business they would not be for a baker.

Remember, you can’t just “write off” everything you purchase simply because you own a business.