I am assuming you do not have start-up or organizational costs at this point, and that the business has been ongoing for some time A deductible business expense is any expense that is ordinary . (common and accepted in your line of work) and necessary (helpful and appropriate for work).
This list may include items not relative to your business: Amortization, Attorney Fees, Auto expenses, Bad debts (if you are on accrual basis of accounting), Cell phones, Charitable contributions (itemized deduction only if sole proprietorship or S-Corp., Business deduction on C-Corp), Club dues, Commissions and fees, Computer software (thru depreciation), Contract labor, Depreciation, Education exp., Employee benefit plans, Gifts to employees/customers, Insurance
expense (other than life), Interest exp., Job-related seminars, Lease exp., Legal and professional fees, License fees, Office exp., Payroll taxes, Removal/clean-up costs, Rent, Repairs, Sick pay, Subscriptions, Taxes, Tax prep fees, Telephone, Tools, Uniforms, Wages. This should encompass most of your expenses.