Understand bonus interest before you chase the top rate.
This page explains what bonus interest is, why banks use it, and why the strongest advertised rate can still be the wrong fit if the conditions, caps, or intro rules do not match your setup.
What bonus interest actually means
A bonus interest savings account usually combines a lower base rate with an extra rate that only applies when you meet the bank's qualifying conditions.
That means the highest advertised number is often conditional, not automatic. If you miss the rules for that month, the rate you actually earn can be much lower.
The most common conditions
The most common qualifying rules are monthly deposit requirements, no-withdrawal rules, balance-growth rules, minimum card transactions, and linked transaction account requirements.
Each of those changes the real effort involved. Two products can show similar top rates while requiring very different behaviour to earn them.
Why the headline rate can be misleading
A strong headline rate does not tell you whether the account has a balance cap, whether the bonus applies to your full balance, or what happens after an intro period ends.
For larger balances in particular, the account with the biggest advertised rate is not always the one that produces the strongest total return over time.
How to use this when comparing accounts
Before acting, check the official bank page for the current rate, the exact monthly conditions, any balance cap, and whether the bonus is limited to new customers or linked accounts.
Use Savings Planner or the relevant guide page to narrow the shortlist, then verify the final product details directly with the bank.