Which of the following describes a tax-qualified retirement plan where annual contributions are formulaically determined?

The description of a tax-qualified retirement plan where annual contributions are formulaically determined aligns with a defined benefit plan. This type of plan specifies the benefits an employee will receive upon retirement, which are often calculated based on factors such as salary history and years of service. In a defined benefit plan, the employer is responsible for funding the promised benefits and calculating contributions based on actuarial formulas to ensure that sufficient funds are available to meet future obligations.

In contrast, a defined contribution plan specifies how much money is contributed annually, but the actual benefit amounts received during retirement depend on the performance of the investments made with those contributions. Therefore, while defined contribution plans are also tax-qualified, they do not fit the premise of being "formulaically determined" in the same way a defined benefit plan does.

Flexible benefit plans provide employees with choices among various types of benefits, rather than a structured formula for contributions. Endowment plans, while offering a sum at the end of a specified period or upon death, do not function as retirement plans in the same way that defined benefit or defined contribution plans do.

Thus, when considering the definition of a tax-qualified retirement plan with contributions determined by a formula, the defined benefit plan is the most fitting answer.