Charity deposits $90 each month into a 401(k) savings account paying 3.69% annually, and her employer offers 50% matching. After 37 years, she'll have $127,699.08 in her account. How much of this balance is interest? Charity deposits $90 each month into a 401(k) savings account paying 3.69% annually, and her employer offers 50% matching. After 37 years, she'll have $127,699.08 in her account. How much of this balance is interest