Add up all the expenses you wish to itemize. If the value of expenses that you can deduct is more than the standard deduction (in 2020 these are: $12,400 for single and married filing separately, $24,800 for married filing jointly, and $18,650 for heads of households) then you should consider itemizing.
Schedule C is the tax form filed by most sole proprietors. As you can tell from its title, "Profit or Loss From Business," it´s used to report both income and losses. Many times, Schedule C filers are self-employed taxpayers who are just getting their businesses started. In addition to those who do well at the start, this group can also include new business owners who make very little or no profit or even lose money. There's also a shorter form, Schedule C-EZ, "Net Profit From Business." You can use the Schedule C-EZ if you have a profit from your business and your expenses are less than $5,000, no inventory, no employees, and you are not using depreciation or deducting the cost of your home. You will need to file Schedule C annually as an attachment to your Form 1040.
Unless exempt under section 501, all domestic corporations (including corporations in bankruptcy) must file an income tax return whether or not they have taxable income. Domestic corporations must file Form 1120, unless they are required, or elect to file a special return.
Use Form 1120-S to report the income, gains, losses, deductions, credits, etc., of a domestic corporation or other entity for any tax year covered by an election to be an S corporation.
Form 1065 is used to declare profits, losses, deductions, and credits of a business partnership. This form is filed by LLCs, foreign partnerships with income in the U.S., and nonprofit religious organizations. Partnerships must also submit a completed Schedule K-1.