NS&I Savings Calculator

NS&I (National Savings and Investments) products are backed by HM Treasury, making them among the safest savings vehicles in the UK with 100% government guarantee (compared to the £85,000 FSCS limit on bank deposits). Products include Income Bonds, Direct Saver, Green Savings Bonds, and Premium Bonds, each with different interest rates, access terms, and minimum deposits.

Interest calculation varies by product. Income Bonds pay interest monthly on the full balance at a variable rate. Direct Saver pays variable interest on balances from £1 upward. Green Savings Bonds offer a fixed rate over a 3-year term with interest paid at maturity or annually depending on the issue. The calculator applies the correct compounding method for each product: monthly compounding for Income Bonds, annual for fixed-term products.

The comparison with high-street banks uses AER (Annual Equivalent Rate) for a like-for-like assessment. NS&I rates are often slightly below the best high-street rates because of the superior government backing. However, NS&I interest is paid gross (no tax deducted at source), and for Premium Bonds, all prizes are entirely tax-free. The calculator factors in your personal savings allowance (£1,000 basic rate, £500 higher rate) to show after-tax comparisons.

What is NS&I? National Savings & Investments — government-backed savings. 100% Treasury-guaranteed. No FSCS protection needed (covered by gov.uk). Major products: Premium Bonds (4.15% prize rate, tax-free); Direct Saver (4.0% easy access); Direct ISA (4.0% cash ISA); Income Bonds (4.0% monthly interest); Junior ISA (4.0%); British Savings Bonds (5-year fix 4.0-4.7%). Used by: ~25 million UK savers. Holds £200+ billion in deposits.

NS&I rates vs market 2026. NS&I Direct Saver: 4.0% AER. Market best easy access: 5.0% (Chase 4.85%, Marcus 4.75%). NS&I 'gap' usually 0.5-1.0% behind market. Premium Bonds 4.15%: matches average savings but unpredictable — half holders earn less, half more. Trade-off: government safety vs ~10-20% lower returns. Holders £85k+ : NS&I beats FSCS limit alternative (split deposits across banks). Most savers: best-rate non-NS&I banks better choice up to £85k FSCS limit per bank.

Premium Bonds — the unique NS&I product. £1 = 1 bond = 1 prize entry. Monthly draw. £1M jackpot × 2; £100k × 4-5; £50k × 9-10; thousands smaller £25-£25k. Max holding £50,000. Average return 4.15% prize rate — but median much lower. £50k holding: ~2 wins/month average; smaller holdings highly variable. Tax-free: especially valuable for higher/additional rate taxpayers (no PSA used). Cash back any time — 1-3 working days.

NS&I tax advantages. Premium Bonds: 100% tax-free winnings. Junior ISA NS&I: tax-free growth for under-18s. NS&I Direct ISA: tax-free within ISA wrapper. Other NS&I products (Direct Saver, Income Bonds, British Savings Bonds): taxable interest (subject to PSA). Don't use Personal Savings Allowance (PSA) if outside ISA. Generally: ISA wrap or Premium Bonds for tax-efficient NS&I.

When to choose NS&I. Best for: Treasury-safety priority (large balances £85k+); higher-rate taxpayers (Premium Bonds tax-free); easy access without daily monitoring; UK government supporters (your savings fund national debt at usually below-market cost). Worst for: maximising returns (typically 10-25% behind best market rates); inflation protection (Index-Linked Savings Certificates closed to new investors since 2011, only existing holders renewing). Best alternative: bank savings up to £85k FSCS limit, plus Premium Bonds for tax-free chance/excitement.