UK Cash ISA Tax-Free Calculator
Savings Deposits & Rate
Configure your initial principal, interest rate, and compounding intervals.
Projected Compound Growth
Principal accumulation, interest yield, and final balance.
Calculation Result
Starting principal
12 monthly deposits of $250
Your total out-of-pocket savings
Current High-Yield & Certificate of Deposit (CD) Benchmarks
Projected annual cash earnings on a $20,000 allocation.
| Institution & Account | APY / AER | Est. Annual Yield | Est. Monthly |
|---|---|---|---|
High-Yield Savings (HYSA)RecommendedTop-Tier Online Bank (US) • Liquid / No lockup | 4.2% | $840/yr | +$70/mo |
Certificate of Deposit (CD)Direct Bank 12-Month CD • 1-Year Guaranteed Term | 4.25% | $850/yr | +$71/mo |
Cash Sweep PortfolioHigh-Yield Cash Account • Same-Day Transfers | 4.1% | $820/yr | +$68/mo |
Standard Checking / SavingsTraditional Brick & Mortar • National Average | 0.01% | $2/yr | +$0/mo |
Advertising & Affiliate Disclosure: ConvertSheet is an independent educational calculation service and may receive compensation from partner financial institutions when users click to compare rates. Zero client data or calculated figures are ever shared.
How Much Interest Does $20,000 Earn at 3.5% to 5.5% APY?
Instant compounding breakdown across daily compounding high-yield savings accounts and fixed certificates of deposit.
| Duration | 3.5% APY Conservative Savings / MMF | 4.0% APY Top National Bank Rate | 4.5% APY Competitive High-Yield (HYSA) | 5.0% APY Top Tier Online Bank / CD | 5.5% APY Peak Promotional / Treasury Bill |
|---|---|---|---|---|---|
| 1 Month | +$58 Balance: $20,058 | +$67 Balance: $20,067 | +$75 Balance: $20,075 | +$84 Balance: $20,084 | +$92 Balance: $20,092 |
| 3 Months | +$176 Balance: $20,176 | +$201 Balance: $20,201 | +$226 Balance: $20,226 | +$252 Balance: $20,252 | +$277 Balance: $20,277 |
| 6 Months | +$353 Balance: $20,353 | +$404 Balance: $20,404 | +$455 Balance: $20,455 | +$506 Balance: $20,506 | +$558 Balance: $20,558 |
| 1 Year | +$712 Balance: $20,712 | +$816 Balance: $20,816 | +$920 Balance: $20,920 | +$1,025 Balance: $21,025 | +$1,131 Balance: $21,131 |
| 2 Years | +$1,450 Balance: $21,450 | +$1,666 Balance: $21,666 | +$1,883 Balance: $21,883 | +$2,103 Balance: $22,103 | +$2,325 Balance: $22,325 |
| 3 Years | +$2,214 Balance: $22,214 | +$2,550 Balance: $22,550 | +$2,891 Balance: $22,891 | +$3,236 Balance: $23,236 | +$3,588 Balance: $23,588 |
| 5 Years | +$3,825 Balance: $23,825 | +$4,428 Balance: $24,428 | +$5,046 Balance: $25,046 | +$5,680 Balance: $25,680 | +$6,330 Balance: $26,330 |
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About UK Cash ISA Tax-Free Calculator
In the United Kingdom, Individual Savings Accounts (ISAs) protect interest and dividends from HMRC income tax. ConvertSheet's Cash ISA Calculator models easy-access and fixed-rate Cash ISAs, helping UK savers forecast compounding returns within their £20,000 annual allowance without risking private banking data on external cloud servers.
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Frequently Asked Questions: UK Cash ISA Tax-Free Calculator
Clear mathematical answers to key questions, calculations, and loan parameters.
What is the UK annual ISA allowance?
The annual UK ISA allowance is £20,000 per tax year (running 6 April to 5 April), which can be distributed across Cash ISAs, Stocks & Shares ISAs, and Innovative Finance ISAs.
Is interest in a UK Cash ISA completely tax-free?
Yes. Interest earned within an ISA is completely exempt from UK income tax and capital gains tax, and does not count toward your HMRC Personal Savings Allowance (PSA).
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