Most insurers will allow you to protect your NCB once you get to 4 years.
There will usually be an additional cost for this and varies customer to insurer. You need to inform the customer of the difference if asked. This information is displayed on the price presentation screen.
Insurers also have different step back scales if a claim happens. This information is found within the policy wording link. See links below -
Highway http://policywording.cdlis.co.uk/LVBroker_GV_PW0120_HighwayVan-2020-01-10-09-07-01.pdf Highway http://policywording.cdlis.co.uk/LVBroker_GV_PW0120_ClearVan-2020-01-10-09-06-48.pdf Covea http://policywording.cdlis.co.uk/Covea_GV_PW0520_CV-2020-05-27-11-05-30.pdf Covea http://policywording.cdlis.co.uk/Covea_GV_PW0520_CV-2020-05-27-11-05-30.pdf Zenith http://policywording.cdlis.co.uk/Markerstudy_ZM_GV_PW0918_Standard-2018-06-28-15-50-12.pdf Zenith http://policywording.cdlis.co.uk/MISL_GV_PW0320-2020-08-18-09-34-49.pdf CPD http://policywording.cdlis.co.uk/CPD_Van_Care_-Nov_21-202112300958.pdf KGM http://policywording.cdlis.co.uk/KGM_CV-C33_0122-202111301505.pdf NIG http://policywording.cdlis.co.uk/NIG_Van_Policy_Booklet-202203171223.pdf Aviva http://policywording.cdlis.co.uk/Aviva_GV_PW0519_Your-Van-2019-05-15-10-27-40.pdf Pukka http://policywording.cdlis.co.uk/CVTM_MLS-_CPWv6-202202171704.pdf Pukka http://policywording.cdlis.co.uk/CV_MLS-PKS-202109081714.pdf Pukka http://policywording.cdlis.co.uk/NIG_Policy_Wording-202209281126.pdf
Premier http://policywording.cdlis.co.uk/Premier_GV_PW1016_UY_U7-2016-10-25-16-00-28.pdf Premier http://policywording.cdlis.co.uk/PREMIER_PUL_PICL_CV_2022-202208221053.pdf AXA http://policywording.cdlis.co.uk/GCV_PW_ACLD0718P-E-202106161405.pdf AXA http://policywording.cdlis.co.uk/GCV_PW_ACLD0718P-E-202106161405.pdf RSA http://policywording.cdlis.co.uk/RSA_GV_PW0519-2019-05-03-14-20-06.pdf Sabre http://policywording.cdlis.co.uk/S_03-22_CV-202201200859.pdf Sabre http://policywording.cdlis.co.uk/S_03-22_CV-202201200859.pdf Southern Rock http://policywording.cdlis.co.uk/SouthernRock_GV_PW0518_Std-2018-07-04-10-38-02.pdf Watford http://policywording.cdlis.co.uk/WICE-CV-Generic-PW-202212161635.pdf Watford http://policywording.cdlis.co.uk/03%20Standard%20CV%20-%20WICE%20-%20Generic%20-%20Policy%20Wording%20-%202020-2021-01-22-10-37-21.pdf BISL http://policywording.cdlis.co.uk/Equity_GV_PW0619_Standard-2019-04-16-13-58-28.pdf BISL http://policywording.cdlis.co.uk/Equity_GV_PW0619_Standard-2019-04-16-13-58-28.pdf
S Kitsune http://policywording.cdlis.co.uk/KTCV112021AIEL-202112061113.pdf Zenith http://policywording.cdlis.co.uk/MISL_GV_PW0320-2020-08-18-09-34-49.pdf Zenith http://policywording.cdlis.co.uk/MISL_GV_PW0419-2019-05-21-10-25-00.pdf Zenith http://policywording.cdlis.co.uk/Markerstudy_GV_PW0618_MISLCV-2018-06-26-13-23-02.pdf