Symptoms

There is no Extension of Time certificate to select within NBS Contract Administrator under the IC & ICD form of contract.

Cause

The form hasn’t been replaced, but rather the terminology has been changed to be called "Adjustment of Completion Date".
 
The decision for this change was because the period for completion can be reduced as well as extended, therefore the term “Extension of Time” was no longer appropriate. This change has been in effect since 2016, when RIBA republished the CA forms to reflect the 2016 JCT editions.

Resolution

Simply use the "Adjustment of Completion Date" certificate.