Isabel is a self-employed electrician. All cash payments she receives from customers are deposited into a bank account held in the name of her son. Isabel does not use the funds. Therefore, she thinks she does not need to include the cash receipts in her gross income. Which concept or doctrine applies to this situation?

a.Assignment-of-income doctrine

b.Arms-length transaction concept

c.Substance-over-form doctrine

d.Pay-as-you-go concept

e.Annual accounting period concept