UK savings comparison rate showing the annual equivalent of interest after compounding, subject to the account's stated rate and conditions.
Annual equivalent rate (AER) is a rate used in the UK savings market to show what an account’s interest rate would produce on an annual basis after compounding. It helps compare savings products that calculate or pay interest at different intervals. AER is a standardized comparison figure, not a guarantee of the interest a particular saver will receive.
The Financial Conduct Authority’s savings-account summary-box guidance permits firms to use AER when presenting interest rates. The account’s rate schedule, balance conditions, access rules, and interest-crediting terms still determine actual earnings.
If (r) is a nominal annual rate compounded in (m) equal periods, its annual equivalent is:
If an account states the periodic rate (i_p) directly:
where (m) is the number of equal compounding periods in a year.
These formulas explain the financial mathematics. For a real account, use the provider’s disclosed AER and terms because day-count methods, tiered balances, rate changes, required transactions, and rounding can affect the calculation.
Assume a savings account has a 4.80% nominal annual rate compounded monthly. The monthly periodic rate is 0.40%:
The annual equivalent rate is:
If GBP 10,000 remains in the account for one year, the rate does not change, and every interest credit remains deposited, the simplified ending balance is approximately:
The modeled interest is GBP 490.70. If the saver withdraws each monthly interest payment instead, those amounts cannot compound in the account, so total interest would be lower under this nominal-rate example.
Suppose two accounts both advertise 4.90% AER:
| Feature | Account A | Account B |
|---|---|---|
| Interest payment | Monthly | Annually |
| Advertised AER | 4.90% | 4.90% |
| Interest left in account | Intended to compound | Credited at year-end |
| Access to interest | Earlier payment dates | Later payment date |
If both providers have calculated the same AER correctly and the comparison assumptions hold, the one-year compounded result should be broadly comparable. Account A’s gross monthly rate will normally be lower than 4.90% because twelve monthly credits build toward the annual equivalent.
The products can still differ in withdrawal rules, minimum balances, bonus conditions, fixed terms, rate guarantees, and tax treatment. Payment frequency alone does not identify the better account.
| Measure | Typical use | Includes compounding? | Important distinction |
|---|---|---|---|
| AER | UK savings-account comparison | Yes | Read with account conditions and payment assumptions |
| Gross Interest rate | Interest before tax or deductions, commonly shown with savings products | Not necessarily | Can differ from AER when interest is paid more than annually |
| EAR | General compounding conversion | Yes | Mathematical concept rather than a market-specific savings label |
| APY | U.S. deposit disclosure | Yes | Calculation and disclosure follow U.S. Regulation DD |
| APR | Borrowing-cost disclosure | Depends on applicable rules | Not the appropriate label for savings earnings |
AER and EAR may equal each other in a simple fixed-rate calculation. The difference is context: EAR is a general effective-rate concept, while AER is a savings comparison convention used by providers in the UK market.
An AER quote is useful only when the rate conditions are understood.
A fixed-rate savings account holds the stated rate for a specified term, subject to its contract. The account may restrict withdrawals or impose consequences for early access. A fixed AER does not mean the funds are available on demand.
The provider may change a variable interest rate under the account terms. The displayed AER describes the rate at the time of the quote, not a promise that the same rate will apply for a full year.
An introductory bonus can expire on a stated date. Other accounts pay a higher rate only if the customer limits withdrawals, makes regular deposits, or satisfies another condition. Compare both the conditional rate and the fallback rate.
Different balances or portions of a balance can earn different rates. Confirm whether one rate applies to the entire balance or each balance band has its own rate. The highest displayed AER may not apply to all deposited funds.
The FCA savings summary box is designed to show rates, estimated balances, access conditions, account management details, and other necessary information together. AER should be read within that broader disclosure, not in isolation.
This page provides general financial education, not deposit, legal, tax, investment, or personalized financial advice. Product terms and applicable UK disclosure requirements control actual rates and earnings.