United Kingdom Financial Glossary
Learn the definitions of key financial terms, tax acronyms, and mortgage jargon commonly used in United Kingdom. Updated for 2026.
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Stocks & Shares ISA Interest Tax
InvestmentsA new 22% flat-rate tax on interest earned by cash held within Stocks & Shares or Innovative Finance ISAs, effective April 2027.
View full definition →Stablecoin
InvestmentsA cryptocurrency pegged to a fiat currency (typically USD or GBP), subject to FCA regulation in the UK from 2026 under the Financial Services and Markets Act 2000.
View full definition →UK financial terms for the 2027 ISA reform and crypto regulation era
The Autumn Budget 2025 rewrote UK savings rules from April 2027: a reduced Cash ISA cap, a new tax on uninvested cash in investment wrappers, and the FCA's expanded crypto authorisation regime. These terms explain the specific mechanisms that affect how you save, invest, and interact with digital assets in the UK.
The 2027 ISA restructuring
Under-65 savers face a new ceiling: £12,000 in Cash ISAs (down from £20,000). The remaining £8,000 of your annual allowance must go into Stocks & Shares or Innovative Finance ISAs to remain tax-sheltered. A flat 22% tax now applies to interest earned on cash held inside S&S ISA wrappers, closing the loophole where people parked cash in investment accounts to dodge the cap. Over-65s are exempt from both changes.
FCA crypto and stablecoin authorisation
The FCA now requires full authorisation (not just AML registration) for crypto exchanges, custodians, and stablecoin issuers operating with UK customers. Stablecoin issuers must hold 100% reserves in approved assets, undergo regular audits, and provide on-demand redemption. Only 45 firms hold active crypto authorisation after an 85% application rejection rate over 6 years.