If you are self-employed (an independent contractor) you are required to keep accurate records of your income and expenses, even if you don't get tax paperwork from the companies that hire you.
You list the business on schedule C, you report income and deduct expenses, and pay income tax and self-employment tax on the net profit. If the business was up and running as of 2020, even if you did not have income, you can deduct your expenses (you have a net operating loss, which may be deducible against any other income you might have.)
You will have to first differentiate between startup costs and ongoing costs. For example, if your business requires specialized equipment, that would be a startup cost, while supplies for the equipment would be an ongoing cost. Some startup costs may be expensed, some must be spread out over 15 years. Equipment must usually be depreciated over it's useful life span, but can sometimes be expensed.
=>You need to create a schedule C business and list your income (if any) and expenses. Equipment or other items generally with a lifespan of more than one year will be listed as assets. Other expenses will be listed in their own categories (advertising, supplies, etc.). Turbotax will tell you if you can expense or depreciate your assets and startup costs and will tell you whether you can deduct your costs against other income this year or in the future when your business starts getting paid.
