Unfortunately (and I only say that as you might not like the answer for this scenario) it is the cost of what it will be now, less the cost of what it would have been. The omission is not however based on your activity schedule , it is a build up of the costs you know know it would have cost you. You have to build this up the same way using the schedule of cost components for both the addition and the omission.
This clause will be your friend when you can prove the original you could have done cheaper than your price you indicated at tender, but equally not your friend if you had put in an unrealistically cheap price against that item. Don't forget as well that the activity schedule is a payment mechanism only, not a reflection of true actual cost for any one item. It may also include an element of prelim type cost so would not be fair to use bluntly as an add/omit value.
This clause will be your friend when you can prove the original you could have done cheaper than your price you indicated at tender, but equally not your friend if you had put in an unrealistically cheap price against that item. Don't forget as well that the activity schedule is a payment mechanism only, not a reflection of true actual cost for any one item. It may also include an element of prelim type cost so would not be fair to use bluntly as an add/omit value.
