An individual and a company are sponsoring an idividual athlete. What do they need from the athlete in order to claim it as a business tax expense.

I have a rental property business in nj and a wedding business in nys.

Just wondering because I am estimating the cost of a business me and my partner are planning on running. I live in the new york city and surrounding areas.We are also planning on running a second location in Los Angeles. Both businesses require automobiles.
Im aware I cant add averages on a tax return, however for car purchasing purposes im just wondering if there is any type of statistics available for people that report mileages on their business vehicles.

Tax wise, I am trying to decide how to set up my business. It am alone, a freelancer and am trying to find out if I should incorporate etc. Thanks.

Shall I write myself checks on the business acct. to pay msyelf back for the items I paid for from the personal acct?

My reasoning: I want all income and expenses clearly accounted for from within the business acct. (and quicken).

Is this an acceptable practice?

Here are 2 questions:
(1) I understand that I can write off business expenses on my tax returns. That includes computer equipment, trips overseas to purchase merchandise, etc. But I’ve never itemized my tax return before. Would I get more money back if I start a business, and then itemize my deductions rather than just taking the default deduction like I always do?

(2) If I make my online selling into an official business, will I have to pay extra business-related taxes?

Additionally, does anyone know of any resources that indicate what the implications are of stopping a home based business write-off?

I see lots of information on how/what to write-off for a home based business, but can’t seem to find anything on what to do when that ends.