NEC ECS: Sub contractor payment dates under NEC Option A

We are contracted under an nec sub contract to a main contractor under option A contract. Our commencement date was 5th Aug with assessment dates set as last Friday of the month. When would our final dates for payments be? The main contractor amended the 3 weeks in their contract to 5 weeks in our sub contract. We have submitted an application for payment in Aug and Sept and have asked for clarification on payment dates but are being told our first payment would be 29th Sept. is this correct???

I assume this is an NEC3 contract and you are referring to 2019, in which case the last Friday of August would be the 30th, which is the first payment assessment date. I assume that the definition of ‘assessment interval’ has been worded to reflect the ‘last Friday of the month’.

The Contractor certifies within 2 weeks of the assessment date, with the latest date being 13th September, with payment made within 5 weeks of the assessment date which is 04th October, not 29th September.

The first 2 sets of payment dates would, therefore, be;

assessment date 30 Aug 27 Sep
certified date 13 Sep 11 Oct
due date 13 Sep 11 Oct
final date for payment 04 Oct 01 Nov