A retention bond, also called a retention money guarantee, is an undertaking that pays the employer up to a fixed sum if the contractor fails to complete the works or to make good defects, and it is given in place of the retention money the employer would otherwise hold back in cash.
On most construction and engineering contracts the employer deducts a retention from every interim payment certificate, commonly a percentage of the certified value, and keeps it as a cushion against incomplete or defective work. That retention is usually released in two tranches: half at practical completion, and the balance at the end of the defects liability period, once notified defects have been remedied. For the contractor the effect is that a slice of earned revenue sits in the employer's account for the whole of the project and well beyond it.
A retention bond substitutes that withheld cash with a bank undertaking. The employer certifies and pays the interim application in full, without deduction, and in exchange receives a bond for an equivalent amount. Its protection is unchanged in substance, because it can call on the bond for the same failures for which it would have applied the retention, while the contractor keeps the money as working capital on site, funding labour, materials and plant instead of financing the employer's security. It is the contractor that normally requests the arrangement and the employer that must accept it, so the wording is agreed before the first application for payment is submitted.
Face value is commonly 5% to 10% of contract value, and it is normally set at exactly the retention percentage stated in the contract, so the bond and the deduction it replaces are equivalent. Many bonds are drafted to reduce at practical completion in the same proportion as the retention would have been released, leaving the balance in force for the defects liability period. Validity therefore usually runs from the first interim certificate to the end of that period, often 12 to 24 months after completion, with an extension mechanism where completion is delayed.
How it is called: where the employer accepts bank-style wording, the retention bond is issued as a demand guarantee under URDG 758 and is payable against a written demand stating that the contractor has failed to complete or to remedy defects, without the employer having to prove its loss first. Conditional wording is also used, particularly under contracts drafted to local law, and then the demand must be supported by the certificates or engineer's statements the bond names. The contractor's obligations are the ordinary ones: keep the bond valid, apply the released cash to the contract, respond to notified defects in writing, and reimburse the issuer for any amount properly paid.
Release mechanics: the bond reduces or expires in step with the retention it replaced. The first reduction follows the certificate of practical completion; the remaining amount expires at the end of the defects liability period, or earlier against a final certificate confirming that defects have been made good. Instruments issued under URDG 758 expire on their own terms even if the original document is never returned.
Illustration: a contractor on a EUR 30 million hospital package would face a 5% retention, EUR 1.5 million, deducted progressively from interim certificates and released half at completion and half twenty-four months later. The employer accepts a retention bond for the same 5% instead, reducing to 2.5% at practical completion and expiring at the end of the defects liability period. The contractor is paid in full on each certificate and keeps EUR 1.5 million of working capital in the project rather than in the employer's account; the employer keeps equivalent recourse throughout.