If a business owner paid for business expenses with their personal account, and those expenses would otherwise be deductible, they:

CANNOT be deducted on the tax return because they weren't paid for from a business account.

CAN be included on the tax return as long as proof of the expenses is sent with the return.

CAN be deducted on the tax return.

CANNOT be deducted because the IRS requires separate business and personal bank accounts.