Before asking someone to be a sponsor for baptism or confirmation, consider that the sponsor’s role is to help the baptized lead a Christian life in harmony with baptism and fulfill faithfully the obligations connected to it.
According to Church Law, a sponsor must:
be designated by the candidate or, in the case of infant baptism, by the candidate’s parents;
be at least 16 years of age (the pastor may make an exception for a just cause);
be Catholic, having received the Sacraments of Initiation (Eucharist & Confirmation);
lead a life in harmony with the faith and the role to be undertaken;
if married, be living in a valid union (a marriage recognized or blessed by the Catholic Church).
Other important points:
a candidate’s parent may not serve as a sponsor;
only one sponsor (male or female) is required but two sponsors, one of each sex, are permitted for baptism;
a baptized non-Catholic Christian cannot be a Catholic sponsor but may assist as a Christian witness. (A baptized Catholic who does not meet all eligibility requirements may not serve as a Christian witness.)
A person’s baptismal sponsor may also take this role at Confirmation provided he/she still meets the criteria above.