6.2. As any changes to the service costs relate to revenue services, any adjustment to the unitary payment should be straightforward. However in certain instances, there could be some interaction between the revenue element of the unitary payment and the total financing for the project and therefore the public sector client will need to gain assurance that the unitary payment is adjusted correctly. Normally the revised cost will apply at the sub-contract level and it is important that the parties are clear how this translates through into a revised unitary payment against the PPP contract. The public sector client will need the assistance of financial advisers to check that this is done correctly. Typically requirements that need to be followed in respect of flowing through the resulting change to the Unitary Payment / Financial Model will be detailed in the contract.