Daily savings interest explained: compounding, credit dates and withdrawals

Savings providers often advertise interest paid daily, monthly or annually. But there are three different events: interest is earned, it is credited to your account, and the money is available to withdraw. Understanding the difference helps you compare accounts and plan for a date when you need the cash.

How daily savings interest is calculated

An account’s annual equivalent rate (AER) describes the effective annual return when its stated compounding assumptions apply and the rate stays unchanged. With a 3.8% AER and daily compounding, the equivalent daily rate is approximately (1.038)^(1/365) − 1, or 0.0102% per day. An initial £10,000 therefore earns around £1.02 on the first day. This is an estimate: providers may use a different day-count convention, rounding policy or nominal-rate calculation.

On the next day, the calculation may start from £10,001.02 if the interest has already been credited. If the provider credits interest monthly, however, the earned interest may not be added to the balance until the payment date. The two arrangements should not be assumed identical just because both say interest is calculated daily.

What compound interest actually means

Compounding is interest earned on interest that has previously been added to the interest-bearing balance. It becomes more noticeable as balances, rates and timescales increase. At a constant 3.8% AER, £10,000 held for one year would grow to approximately £10,380 when the product delivers that effective annual return. Do not apply 3.8% every month: that would hugely overstate the return.

Use the Savings Interest Calculator to compare crediting frequency, regular deposits and the amount still awaiting payment. For a specific savings target, the Savings Goal Calculator works backwards to the monthly contribution needed.

Interest earned versus interest credited

Suppose an account calculates interest each day but pays monthly. Midway through the month you may have accrued interest that has not appeared in the account’s available balance. If the provider has a further processing delay, interest earned today could reach the account later still. This does not necessarily mean that withdrawing your existing cash takes the same number of days.

Different products from the same provider can have different schedules. For example, terms may differ between a cash ISA and uninvested cash in an investment account. Consult your individual product’s current terms rather than assuming a particular seven-day delay.

Planning around a cash-out date

If you need a house deposit or holiday payment on a known date, distinguish the credited balance from pending interest. Separately check whether your account allows instant withdrawals, charges notice penalties or needs additional working days to transfer funds to your bank. Weekends, identity checks and bank cut-off times can affect arrival. A calculator can estimate interest accrual; it cannot guarantee transfer completion.

Do savings tax and inflation matter?

Yes. The interest calculation is normally before any tax liability, and a positive interest rate does not automatically preserve purchasing power. Check the Personal Savings Allowance Calculator for a simplified UK tax illustration and Inflation vs Savings to compare interest with assumed price rises.

Checklist before choosing an account

• Confirm whether the quoted rate is AER, gross annual or a promotional rate.
• Check whether and how frequently the rate can change.
• Read the terms for interest calculation, crediting and compounding.
• Check cash withdrawal limits, notice rules and transfer timing independently.
• Compare after-tax returns where relevant, and check whether your savings fall within deposit protection limits.

For neutral help comparing accounts, consult MoneyHelper’s savings account guidance. This guide is educational and not a promise of a particular rate or payment date.

If you’re turning interest assumptions into regular contributions towards a target, try monthly savings goal guide.