(1) Section 256(4) of the Sentencing Code (limits on extension period in term of extended sentence of detention) is amended as follows.

(2) In paragraph (b) -

(a) in sub-paragraph (i), at the end insert "(unless sub-paragraph (iii) applies)";

(b) in sub-paragraph (ii), at the end insert "(unless sub-paragraph (iii) applies)";

(c) after sub-paragraph (ii) insert -

"(iii) 10 years in the case of a serious terrorism offence for which the sentence is imposed on or after the day on which section 16 of the CounterTerrorism and Sentencing Act 2021 comes into force."

(3) In the words after paragraph (b), for "and "specified terrorism offence"" substitute ", "specified terrorism offence" and "serious terrorism offence"".