Was certification expiration changed due to test-center closures during 2020?

Yes, all NSE 4–7 certifications valid on March 16, 2020, the date of Pearson VUE test center closures, were extended by six months. NSE certifications that expired prior to March 16, 2020 were not extended. New certifications that were granted after March 16, 2020 continue to have a two-year expiration date. 

However, NSE 8 certification expirations were not extended by six months. For NSE 8 certifications valid on March 16, 2020, the opportunity to retest was extended from 30 days after expiry to 180 days. The additional six months provided more time to re-certify while averting certification expiry during the time that testing at Pearson VUE was not available. It did not change the certification validity period, nor add six months to the certification expiry date.