Index-Linked Savings Calculator UK 2026
Calculate the real value of index-linked savings and NS&I certificates. See how inflation-linked savings compare to fixed-rate accounts in real terms.
Index-Linked Savings Calculator 2026
Frequently Asked Questions
What are NS&I index-linked savings certificates?
NS&I (National Savings and Investments) index-linked savings certificates are government-backed savings that grow in line with RPI (Retail Prices Index) plus a small fixed rate of interest. They have historically been popular because the returns are tax-free. NS&I periodically opens and closes them; when available they typically come in 2-year and 5-year terms.
Are index-linked savings tax-free in the UK?
NS&I index-linked certificates are tax-free — all growth is exempt from income tax and capital gains tax. Other index-linked savings products (such as inflation-linked bonds from banks) are not automatically tax-free; interest is taxed as income above the Personal Savings Allowance (£500 for higher rate taxpayers, £1,000 for basic rate). Holding them in a Cash ISA removes any tax liability.
RPI vs CPI — which is better for savers?
RPI (Retail Prices Index) typically runs 0.5–1.5% higher than CPI (Consumer Prices Index) because of its different methodology (it includes mortgage interest costs and uses arithmetic mean). For savers, RPI-linked savings therefore usually produce a higher nominal return. However, the ONS has designated RPI as a flawed measure; most newer government-backed products use CPI. The Bank of England targets CPI at 2%.
How do I buy NS&I index-linked savings certificates?
NS&I certificates are not always available. When open for sale, you can apply directly at nsandi.com or by phone. Existing holders can roll over maturing certificates even when NS&I is not accepting new applications. Certificates must be held for the full term (2 or 5 years) to receive the full index-linked return; early encashment typically receives a lower rate.
What happens when NS&I certificates mature?
When your NS&I index-linked certificate matures, NS&I usually writes to you and gives you the option to roll over into a new issue (if available), transfer to another NS&I product, or encash. If you do nothing, the certificates are generally held on a variable rate extension. It is important to act at maturity to avoid losing the index-linked benefit.