"Those who bless and pass the sacrament should dress modestly and be well groomed and clean. Clothing or jewelry should not call attention to itself or distract members during the sacrament. Ties and white shirts are recommended because they add to the dignity of the ordinance. However, they should not be required as a mandatory prerequisite for a priesthood holder to participate. Nor should it be required that all be alike in dress and appearance. Bishops should use discretion when giving such guidance to young men, taking into account their financial circumstances and maturity in the Church."

Handbook 2 20.4.1