Answered: NEC ECC: If the Subcontractor fails to submit a compensation event quotation, is there a date in which the Contractor has to notify their intent to assess the CE?

In short no. In fact, they do not respond with their quotation within the period of reply but within the period stated in the contract, which unless amended with a Z clause will be  one week. Clause 64.1 states that if the Subcontractor has not submitted the quotation within the timescale then they assess themselves. You do not actually have to notify of your intent to assess yourself as Contractor - it is your automatic right. This does of course has to be a fair assessment in accordance with the contract, otherwise if implemented but Subcontractor does not agree that could lead to adjudication.