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TrustFinance Research Team
Oct 09, 2026
4 min read
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First check whether each rate applies only to a balance band or to the entire balance after a threshold is reached. The two methods can produce very different interest on the same deposit. Calculate using your actual balance, eligible days and product conditions rather than multiplying the full deposit by the largest advertised rate.
For a hypothetical marginal-tier account, assume the first 10,000 currency units earn 1% per year, the next 10,000 earn 2%, and the balance above 20,000 earns 3%. A constant balance of 25,000 therefore contains three portions: 10,000, 10,000 and 5,000. We use simple annual interest, no compounding, fees or taxes and no changes in rates or balance. The currency units are deliberately generic; these are not rates offered by a real bank.
For a whole-balance account, the threshold can select one rate for the full balance instead. Under the same hypothetical thresholds, if the account explicitly pays 3% on the whole 25,000, annual simple interest is 750, not 450. The terms determine which method applies. CFPB’s US Regulation DD appendix describes both tiering methods, and its definitions describe tiered-rate accounts. Those US sources clarify terminology, not local disclosure obligations in every country.
| Balance portion | Annual rate | Simple annual interest |
|---|---|---|
| First 10,000 | 1% | 100 |
| Next 10,000 | 2% | 200 |
| Remaining 5,000 | 3% | 150 |
| Total 25,000 | Weighted rate 1.8% | 450 |
The weighted simple rate is 450 ÷ 25,000 = 1.8%. With a 365-day basis and an unchanged balance for 30 days, the illustrative interest is 450 × 30 ÷ 365 = 36.99 after rounding. Actual statements can differ because of daily balances, a different day-count basis, compounding, rounding, taxation or eligibility rules. A nominal annual rate is not automatically the same as annual percentage yield. Promotional or bonus rates may require transactions or expire after a fixed period. Before comparing accounts, test both your expected balance and a lower balance after withdrawals, and check whether a cap or condition removes the bonus.
Your country of residence, the provider’s contracting entity, the product and your customer classification all matter. A rule described by a UK, Australian or US regulator is an example within that jurisdiction, not a promise that the same protection applies elsewhere. Use the current local regulator’s website and the terms that actually govern your account. If you are unsure which entity or law applies, obtain a written explanation before committing money.
Keep a comparison record containing the date, product name, contract version, relevant amounts and the answers you receive. A screenshot of an advertisement is useful context, but it cannot replace the binding terms or an official register. Recheck before acting because rates, charges and permissions can change. Reviews can highlight questions about service quality, but they cannot establish a licence, a guaranteed return or your legal entitlement. This guide is general education; the numerical examples are editorial assumptions, not live quotations, and no provider is recommended.
Only if the product terms explicitly apply that rate to the whole eligible balance. Marginal tiers require separate calculations.
No. It is a simplified hypothetical result. Use your actual daily balances and the bank’s current calculation method.
2026-10-09 (Asia/Bangkok)
International transfer costs: compare fees and the amount received
TrustFinance Research Team
Official TrustFinance research and editorial team, sharing insights, analysis, and best practices to help financial companies and traders build transparency, credibility, and growth.
