One of the most widespread financial myths is that a raise can hurt you by "bumping you into a higher tax bracket." It cannot. The US income tax system is progressive, which means only the income within each bracket is taxed at that bracket's rate. No extra dollar of income is ever taxed at more than 100% — and reaching a higher bracket never reduces your overall take-home pay. Understanding how marginal tax rates work is foundational to tax planning, retirement contributions, and dozens of financial decisions.
How Tax Brackets Actually Work
Think of tax brackets like buckets. As income flows in, it fills each bucket at that bucket's rate. Once a bucket is full, any additional income moves into the next bucket and gets taxed at the next rate. Income in the earlier buckets is never re-taxed at the higher rate.
2025 Federal Tax Brackets (Single Filers)
| Tax Rate | Taxable Income Range | Tax on This Bracket |
|---|---|---|
| 10% | $0 – $11,925 | Up to $1,193 |
| 12% | $11,926 – $48,475 | Up to $4,386 |
| 22% | $48,476 – $103,350 | Up to $12,073 |
| 24% | $103,351 – $197,300 | Up to $22,540 |
| 32% | $197,301 – $250,525 | Up to $17,030 |
| 35% | $250,526 – $626,350 | Up to $131,557 |
| 37% | Above $626,350 | 37¢ on each dollar above |
These apply to taxable income — your adjusted gross income minus the standard deduction ($15,000 for single filers in 2025) or itemized deductions. Source: IRS 2025 Rev. Proc.
Example: $80,000 Income Step by Step
A single filer with $80,000 in gross income. Subtract the 2025 standard deduction: $80,000 − $15,000 = $65,000 taxable income.
| Bracket | Income in This Bracket | Tax Rate | Tax Owed |
|---|---|---|---|
| 10% | $11,925 | 10% | $1,193 |
| 12% | $36,550 ($48,475 − $11,925) | 12% | $4,386 |
| 22% | $16,525 ($65,000 − $48,475) | 22% | $3,636 |
| Total Federal Tax | $9,215 | ||
This person's marginal rate is 22% (the bracket they land in). Their effective rate is 14.2% ($9,215 ÷ $65,000). They are NOT paying 22% on $65,000. They are paying 22% only on the $16,525 of income that falls into the 22% bracket.
Marginal vs. Effective Rate
| Marginal Rate | Effective Rate | |
|---|---|---|
| Definition | Rate on your last dollar of income | Average rate across all income |
| Use case | Evaluate value of deductions & contributions | Understand your actual tax burden |
| $80K income example | 22% | ~14.2% |
| $150K income example | 24% | ~19% |
How to Use Your Marginal Rate
Value of a traditional 401(k) or IRA contribution
Every dollar you contribute to a traditional 401(k) reduces your taxable income. In the 22% bracket, a $6,500 IRA contribution saves you $1,430 in federal taxes ($6,500 × 22%). This is the "discount" the government gives you on retirement savings.
Roth vs. Traditional: the marginal rate guides you
If you expect your tax rate to be higher in retirement than now, a Roth account (pay taxes now at your current marginal rate) is likely better. If you expect a lower rate in retirement, a traditional account (defer taxes until withdrawal) usually wins.
Evaluating a raise, freelance income, or side gig
If you are in the 22% bracket and earn an extra $5,000 in freelance income, you will owe approximately $1,100 in additional federal income tax (plus ~15.3% self-employment tax if it's self-employment income). Knowing this helps you set aside the right amount for taxes rather than getting surprised at filing.
Key Takeaways
- Tax brackets are progressive — only income within each bracket is taxed at that rate. A raise never reduces your overall take-home pay.
- Marginal rate = the rate on your last dollar of income. Effective rate = your average tax rate across all income.
- A single filer earning $80,000 has a 22% marginal rate but pays an effective rate of about 14%.
- Your marginal rate determines the real value of every 401(k) contribution, IRA deduction, and itemized deduction.
- If your marginal rate will be higher in retirement, favor Roth accounts. If lower in retirement, favor traditional accounts.
For a complete overview of how compound interest, retirement planning, inflation, savings, and FIRE all connect, see our Investing Basics guide.