The delay means that PINS will make its recommendation to the secretary of state outside of the three month deadline for submitting advice following an examination set out in the 2008 Planning Act.
A statement on the PINS website says that a revised deadline for the submission of the inspectorate’s recommendation is now in effect under regulation 9(5) of the Infrastructure Planning (Fees) Regulations 2010.
The statement says that the new deadline for making the recommendation is 5 December 2012.
The regulations stipulate that if an applicant fails to pay a final payment on time PINS may extend the deadline for reporting to the secretary of state.
A spokesman for PINS confirmed that the payment of the final fee for the examination of the application had not been received on time leaving it unable to make the recommendation. The payment has now been received, the spokesman said.
According to the spokesman, the outstanding fee had been £88,071. This was the cost of the 124-day examination – charged at £1,230 a day – less an initial payment of £64,449 made by Vattenfall on submitting the application.
The spokesman said that the case was the first time PINS has extended the deadline for making a recommendation to the relevant secretary of state.
A spokesman for Vattenfall said: "Vattenfall notes that the Planning Inspectorate has slightly delayed passing its recommendation to ministers for our proposed 17 turbine extension to Kentish Flats Offshore Wind Farm.
"Nevertheless, we still expect an irrevocable decision from Ministers in April next year for a scheme that will do much to support the local economy and contribute to delivering renewable energy targets."