Form 15 CA and 15 CB

Form 15CA is mandatory if remittance is made to NRI or Foreign Company (What PART is to be to filled that depends on your case)
Whereas Form 15CB is required if such remittance is liable to tax i.e. TDS and such remittance or total remittance to such party exceeds ₹5 lakhs in a year. Form 15CB is issued by a CA wherein he/she certifies that tax has been deducted properly on such transfer.

And the remittance is to be done in installments...so forms 15ca and cb are required to be filled everytime??