4. Invoice, Payment, Taxes
4.1 GPSC shall issue invoice in Thai Baht, on a monthly basis, indicating the total services fees together with sufficient detail to indicate how such amounts have been calculated in accordance with the provision of this Agreement for the services rendered under this Agreement. In case of reimbursable and/or out-of-pocket expense, each invoice shall be accompanied by all relevant supporting documents, receipt and other justifying document as may be reasonably required by NSC.
The exchange rate used to convert applicable rates, charge and other reimbursable expenditures originated in foreign currencies, other than Thai Baht shall be an average of the buying and selling rates announced by the Bank of Thailand 2 business days before GPSC invoice date.
4.2 Subject to withholding Tax deduction as required by applicable laws, NSC shall pay the invoiced amount in full, without set off, by write transfer in immediately available fund to GPSC designated bank account in accordance with GPSC payment instruction, and payment shall be due within 30 days after NSC receive, and approves such invoice, provided that the approval shall not be unreasonably withheld.
4.3 If NSC reasonably disputes an item billed, NSC shall, within 30 days of receiving GPSC invoice, notify GPSC of the item in dispute, specifying NSC objection. In such case, NSC shall not delay payment of the undisputed part of the invoice. NSC may withhold payment of item in dispute without interest until the dispute is resolved. The Parties shall us all reasonable endeavors to resolve any such dispute as soon as reasonably endeavors to resolve any such dispute as soon as reasonably practicable.