To the extent that the PPP contract provides for the government to make service payments over the life of the contract (as opposed to users paying directly, as in the case of toll roads), the PPP gives rise to a liability. The liability is equivalent to debt and is likely to be counted as such. The size of the liability is the discounted sum of the service payments and is in practice likely to be equal to the construction cost plus the net present value of the operating and maintenance costs over the life of the contract.
The actual parliamentary appropriation, however, is not required until the contract is signed.
The Treasury should be consulted on the accounting treatment for any specific proposal.