Section 19K. In any town, that accepts this section, a town clerk who has completed the necessary courses of study and training, and has been awarded a certificate by the Massachusetts Town Clerks' Association as a certified Massachusetts municipal clerk, shall receive as compensation from such town, in addition to the regular annual compensation paid by such town for services in such office, an amount equal to 10 per cent of such regular annual compensation, but not more than $1,000 per year. In order to qualify for such additional compensation, a town clerk shall submit to the board of selectmen of such town proof of the award of such certificate. The additional compensation provided in this section shall be prorated for any 12 month period in which an eligible person does not hold the office of town clerk for 12 consecutive months. Such additional compensation shall discontinue when certification is discontinued or withdrawn.