I manage a band and want to pay a studio to record them—I have both a business and personal account with funds. How is my equity affected if I pay out of either to the studio?
Basically, any money you put into the business with personal funds is a loan into the business to be paid back. Lets say you put in $10. At the end of the year you profit $100 dollars. That $100 goes back to you as owner, however only $90 of it is considered taxable money since the 10 is just a payback of the loan.
That's the simplified version, assuming you're an LLC or S-Corp. Talk to an accountant to get advice relevant specifically to you.
Personal Funds are loans to the Company or Equity Contributions. This does not change your net income or what is taxable to you as the owner. If the Business nets $100, then you pay tax on $100. You can chose to pay yourself back with the $100 or not.