27 October 2021
A positive leap second was inserted in the national reference time UTC(OP) on 31 December 2016:
2016-12-31 T 23h 59min 59s 23h 59min 60s 00h 00min 00s (UTC)
2017-01-01 T 00h 59min 59s 00h 59min 60s 01h 00min 00s (Local time)
A positive leap second introduced in UTC timescale at the end of december 2016 in application of International Earth Rotation Service (IERS) circular C52.
More information here