An issue has been identified where the percentage of retention after a certificate of practical completion has been issued, is calculated at the pre-practical completion rate.

This is caused by giving the interim certificate an issue date preceding the practical completion issue date.

The incorrect percentage of retention is shown on the interim certificate, after you have issued it. (This is not shown on the draft copy).

An example scenario;

Full retention is 5%
Retention post practical completion is 2.5%

A practical completion certificate has an issue date of 10 July 2013.
An interim certificate with an issue date of 09 July 2013 is issued.

The amount payable on the interim certificate should be calculated at 97.5% of the value of work executed (because it was issued after practical completion). However because it has an issue date before the practical completion it is calculated at the full retention rate of 95%.

The net amount for payment is 2.5% short of what it should be.

This affect specific contracts only. It affects:
  • Minor Works Building Contract 2011 MW 11
  • Minor Works Building Contract with Contractor's Design 2011 MWD 11
  • SBCC Scottish Minor Works Building Contract 2011 MW/SCOT 11
  • Intermediate Building Contract 2011 IC 11
  • Intermediate Building Contract with Contractor's Design 2011 ICD 11

This affects NBS Contract Administrator versions 2.2.5, 2.2.6 and 2.2.7.

Please note the same scenario can happen if both the interim certificate and practical completion are in draft form and the issue date of the interim certificate is set back after the practical completion is issued.

More information

With some JCT and SBCC contracts, the percentage retained changes after practical completion is certified. By default in NBS Contract Administrator, the percentage retained is 5% before practical completion and 2.5% thereafter.


NBS Contract Administrator does not validate the issue date on interim certificates. If a issue date is used, that precedes the issue date of the practical completion, the pre-practical completion percentage rate is used in calculating the amount payable.


Interim certificates issued post practical completion should be dated the same day or later than the practical completion certificate.

To correct the interim certificate, recall the certificate and correct the date.

If more than one form has been issued on the job after the affected interim certificate was issued, we recommend correcting the job using a new Job in Progress.

You should update your software from the prompt in the lower right corner of the screen to prevent this from happening in future jobs.