A letter to be provided by a consultant in favour of a third party (such as a lender or potential purchaser of an asset) to allow that third party to rely on the consultant's report. It is commonly provided to enable effective due diligence and will usually be required by a lender as a condition precedent to financial close under a facility agreement.

The letter also sets out the scope on which reliance is provided and includes standard limitation language to allow the consultant to manage its potential liability to the relying party.