Ошибка с триггером и функцией

CREATE FUNCTION add_money() 
RETURNS TRIGGER 
    AS '
    DECLARE
    surcharge FLOAT;
    premium DECIMAL (20, 2);
    salary DECIMAL(20,2);
    sick_koef FLOAT;
    tax FLOAT;
    
    BEGIN
    sick_koef := 1;
    surcharge := 1;
    premium := 0;
 
    
    salary := (SELECT P.summ FROM position P,worker W 
        WHERE new.worker = W.id_worker AND W.position=P.id_position);
    
    IF(EXISTS (SELECT P.summ FROM premium P, worker W,premium_worker PW  
        WHERE new.worker = W.id_worker AND W.id_worker=PW.id_worker AND PW.id_premium=P.id_premium))
    THEN 
        premium = (SELECT P.summ FROM premium P, worker W,premium_worker PW  
            WHERE new.worker = W.id_worker AND W.id_worker=PW.id_worker AND PW.id_premium=P.id_premium);
    END IF;
    
    IF(EXISTS (SELECT S.percent FROM surcharge S, worker W,surcharge_worker SW  
    WHERE new.worker = W.id_worker AND W.id_worker=SW.id_worker AND SW.id_surcharge=S.id_surcharge))
    THEN 
        surcharge = ((SELECT SUM(S.percent) FROM surcharge S, worker W,surcharge_worker SW  
            WHERE new.worker = W.id_worker AND W.id_worker=SW.id_worker AND SW.id_surcharge=S.id_surcharge)/100) + 1;
    END IF;
 
    UPDATE accrual SET summ = salary * surcharge + premium;
        
        RETURN new; 
    END;'
 
    LANGUAGE 'plpgsql';
CREATE TRIGGER kek
AFTER INSERT ON accrual 
EXECUTE PROCEDURE add_money();