Total estimate $2,600 Retainer $1000 TOTAL outstanding based on estimate, $1600 First invoice $1530 (out of $2600 total estimate) PAID toward invoice $1000 THEREFORE, $530 of invoice unpaid (BUT a $1000 sitting in retainer that has not been applied to my account) The question is Does the contractor have to apply some or all of the retainer toward the invoices?