Use this Bank Account Bonus Calculator to estimate after-tax bonus value, fees, forgone interest, annualized return, and the gross break-even offer clearly.
Bank Account Bonus Formula
A bank bonus should be evaluated after estimated taxes, account fees, other costs, and the interest the qualifying deposit could have earned elsewhere.
After-Tax Bonus = Bonus * (1 - t) Opportunity Cost = Deposit * [(1 + APY)^(d / 365) - 1] Net Value = After-Tax Bonus - Fees - Opportunity Cost
Variables:
- t is the estimated tax rate on the bonus
- Deposit is the qualifying balance kept in the account
- APY is the alternative annual percentage yield written as a decimal
- d is the number of days funds remain tied to the offer
- Fees include monthly maintenance and other entered costs
The simple net return and annualized return on the qualifying deposit are:
Simple Return = Net Value / Deposit Annualized Return = (1 + Net Value / Deposit)^(365 / d) - 1
Break-even mode works backward from taxes, fees, and opportunity cost to find the gross advertised bonus needed for a zero net benefit.
Break-Even Gross Bonus = (Fees + Opportunity Cost) / (1 - t)
Bonus Value Reference
The table assumes a $10,000 qualifying deposit held for 90 days, no fees, and no tax. The alternative account APY is 4.25%, creating about $102 of foregone interest.
| Advertised bonus | Net value after opportunity cost | Simple net return | Approx. annualized return |
|---|---|---|---|
| $100 | -$2 | -0.02% | About -0.08% |
| $200 | $98 | 0.98% | About 4.03% |
| $300 | $198 | 1.98% | About 8.25% |
| $500 | $398 | 3.98% | About 17.18% |
Example Problems
Example 1: Net value of an offer.
A $300 bonus requires $10,000 for 90 days. Estimated tax is 24%, so the after-tax bonus is $228. The account charges three $12 monthly fees, and an alternative 4.25% APY would have earned about $102. Net value is approximately 228 – 36 – 102 = $90.
Example 2: Find the break-even bonus.
Using the same $36 of fees, $102 opportunity cost, and 24% tax rate, the after-tax value needed is $138. The gross break-even bonus is 138 / 0.76 = about $181.58.
Frequently Asked Questions
Are bank account bonuses taxable?
They are commonly reported as interest or other taxable income in the United States, but individual treatment can vary. Enter an estimated tax rate for planning and use tax documents or professional advice for filing.
Why include alternative APY?
A qualifying balance may earn little or no interest while it is tied to the offer. Opportunity cost measures what that money could have earned in another deposit account during the same period.
What offer requirements are not calculated?
Direct deposits, new-money definitions, geographic restrictions, prior-customer exclusions, minimum transaction counts, account-opening deadlines, and retention periods can determine whether the bonus is paid at all.
