MULTIPLEX'S £120,000 a day penalty charges for finishing Wembley Stadium late do not kick in until the summer.
The firm has negotiated a moratorium on the payments, which were supposed to begin on February 1 ? the day after the original completion date.
In all, Multiplex will have to pay £14 million with a further £23 million due to Wembley National Stadium provided by the firm's insurers.
The moratorium ends on May 31 and Multiplex is expected to agree to the charges starting the following day.
But it has told WNSL it is entitled to 'substantial and legitimate extensions of time under the terms of its construction contract' and will try to recover the £14 million when it begins legal action against WNSL.
Included in the £150 million figure it will claim from WNSL will be £20 million in unnecessary building acceleration costs. It will argue that an offer WNSL made before Christmas to agree to an extension in the contract completion time of mid-May was tantamount to admitting this year's FA Cup Final would not be held there.
It will cite FA chief executive Brian Barwick's claim in February, when he announced the Cup Final would be switched to Cardiff, that Multiplex had failed to provide a '100 per cent guarantee' over delivery.
At the end of January, three weeks earlier, Multiplex's UK managing director, Martin Tidd, put the chances of completion at just 70 per cent. It will argue the FA should have taken the decision to move the game then.