The IRS refers to these as 'business start-up costs ', which are the expenses you incur before your business begins, and 'organizational costs ', which are the expenses you incur during the process of setting up your business.
https://www.irs.gov/newsroom/heres-how-businesses-can-deduct-startup-costs-from-their-federal-taxes
Your LLC can elect to deduct up to $5,000 of business startup costs and up to $5,000 of organizational costs paid or incurred in the first year of filing a return. The remaining costs must be amortized (spred out) any remaining costs over a 180 month period. Assuming your expenses are not over $50,000.
The LLC filing costs are examples of organizational costs.
