NEC3 ECC: Change in quantity under option D

Say the Original BOQ for Pile Test 500 ea @ £100, then qty later revised /reduce (due to redesign by owner) to 300 ea, with 100 ea already done @ £50 (actual cost each) and 200 not yet done. What is the correct approach to reduce the Target Price using Option D?

The guidance note says that you consider the actual define cost for works already done plus forecast the defined cost. Is the result of this becomes the new price? or do u have to deduct the result from the original target cost for the item, to get the revised target cost?

if I’m understanding your question correctly.

The original Total of the Prices included 500 pile tests at £100 each so £50,000.

There has been a compensation event revising the Works Information such that there is now only 300 pile tests required.

The quotation should be based on the change in Defined Cost which in this case would be a reduction of 200 tests at £50 each + fee (either direct or subcontract depending on how the work is to be delivered). Assuming 10% fee = -£11,000 adjustment to the Prices. You will also need to consider if the CE alters planned Completion (does it save time) and any risks the contractor carries…