The new British ISA will be introduced in tax year 2024/25.  It will have a £5,000 allowance in addition to the current £20,000 allowance.  The contributions made to this ISA will be invested in British business.  You could therefore allocate up to £25,000 per year across your ISAs.  The date of introduction of the ISA is unknown, but an update is expected from 6 Jun 24 onwards, after a consultation on the ISAs objectives and implementation is carried out.  This page will be updated once more details are known.