Section 108P. In any city, town or district that accepts this section, a collector or a treasurer who has completed the necessary courses of study and training and has been awarded a certificate by the Massachusetts Collectors and Treasurers Association as a certified Massachusetts municipal collector or a certified Massachusetts municipal treasurer or a certified Massachusetts district treasurer, shall receive as compensation from such city, town or district, in addition to the regular annual compensation paid by such city, town or district 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. A collector or treasurer who has been awarded both certificates referred to above shall receive such additional compensation for only one such certificate. In order to qualify for such additional compensation, a collector or treasurer shall submit to the mayor or the board of selectmen of such city or town, or the governing board of a district proof of the award of either or both such certificates. 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 collector or treasurer for 12 consecutive months. Such additional compensation shall be discontinued when certification is discontinued or withdrawn.