1Individual Savings Account Regulations 1998 (SI 1998/1870), as amended: legal framework establishing all ISA types, eligibility conditions, and annual subscription limits. Key amendments include SI 2014/654 (Innovative Finance ISA) and SI 2024/356 (multiple subscriptions per year).
2HMRC ISA Technical Guidance (March 2024): confirms April 2024 change allowing subscribers to open and pay into multiple ISAs of the same type in one tax year, ending the one-ISA-per-type restriction. Also confirms Cash ISA minimum age raised from 16 to 18.
3Lifetime ISA Regulations 2017 (SI 2017/336): sets LISA eligibility (must be 18–39 to open; contributions permitted to age 50), 25% government bonus (max £1,000/year), qualifying home purchase conditions (property ≤ £450,000; first-time buyer; purchased with mortgage; account held ≥12 months), and the 25% withdrawal charge for non-qualifying withdrawals (effective withdrawal cost since April 2021: ~6.25% of own contributions).
4Finance Act 2016, Schedule 13: primary legislation creating the Lifetime ISA and granting HMRC powers to pay bonuses and collect withdrawal charges from LISA managers.
5HM Treasury Autumn Budget 2024: ISA annual allowance confirmed at £20,000 for 2024/25; LISA annual sub-limit confirmed at £4,000 with maximum government bonus of £1,000 per tax year. No changes to ISA allowances announced for 2025/26 at time of publication.