Additional Voluntary Contributions -- Extra payments made by a worker into a tax-deferred savings account (e.g. 401(k) or 403(b)) after the limit till which the employer makes a corresponding investment. Though these contributions may be made on a pretax or aftertax basis, tax law lays down restrictions on the total payment into a tax-deferred account. However, all contributions build up and are not subject to taxation until they are taken out at the time of retirement. The employee chooses the ways in which the money is to be invested.