Under the FIDIC Red Book (edition 1999), if the Contractor as per Sub-Clause 14.

According to FIDIC Red Book 1999, Sub-Clause 14.2, the Advance Payment Guarantee must be a bank guarantee issued by a reputable bank acceptable to the Employer. This bank guarantee serves as security to ensure that the advance payment made by the Employer will be repaid if the Contractor fails to fulfill contractual obligations. The bank guarantee is a commonly used, reliable instrument providing direct financial assurance to the Employer.

Other instruments like surety bonds or parent company guarantees may be acceptable only if explicitly agreed, but the standard requirement is a bank guarantee.

Declaration of joint and several liability is not a typical form of guarantee for advance payments.