Another important reason to keep these funds and transactions separate would be the very real risk of ruing the legal liability protection in place for the business.
Commingling literally is taking personal and business funds and mixing them. But many business owners commingle the funds in the legal sense by simply treating the business account as personal funds. This could include paying for personal expenses straight from the business accounts; hitting the ATM for cash that will be used for personal reasons; mixing the use of a credit card for both business and personal reasons; or transferring money between business and personal accounts without clear records of the transactions.
By commingling your funds, you could be at risk of losing any liability protection better known as “piercing the corporate veil.” This would allow someone to sue your business and be able to have your personal assets attacked as well. Also, because the practice is outside the tax rules, there could well be additional scrutiny during an IRS audit that could include both your personal and business accounts.
Commingling funds could also complicate getting a loan as it creates the lack of distinction between business and personal transactions. So, the lender could have concerns about giving a business loan or a personal loan as they can be sure of the funds for payment or how the funds from the loan would be used.