I have several start up costs related to cost of goods sold, others for advertising, others for supplies, etc. Can I make one entry grouping (COGS, Advertising, Supplies) or do i have to itemize each and every one? There are hundreds, upward of a thousand!
No, you don't need to make hundred of entries. You can deduct up to $5,000 in start-up expenses and anything above that is required to be amortized. According to the IRS, start-up costs can be amortized (deducted) over 180 months.
You can enter the costs up to $5,000 as you would report typical expenses. In other words, if you had $1,000 in legal fees and nothing else, simply report a $1,000 legal fee expense on Schedule C.
Here's how to report amortizable start up expenses in TurboTax Online:
Here is an article you may find helpful: Start-up Business Tax Tips