Taxes
Taxes are your single largest expense. Understanding how they work is worth thousands of dollars every year. You don't need to be an expert, you need to know enough to avoid overpaying and make smart decisions.
Note: figures below reference the 2024 tax year. Bracket thresholds, standard deduction, and contribution limits update annually, so check irs.gov for current-year amounts before filing or planning.
How Income Tax Works
Federal Income Tax Brackets (2024)
The US uses a progressive tax system. You don't pay one rate on all income, you pay increasing rates on each portion.
| Tax Bracket | Single Filer | Married Filing Jointly |
|---|---|---|
| 10% | $0 - $11,600 | $0 - $23,200 |
| 12% | $11,601 - $47,150 | $23,201 - $94,300 |
| 22% | $47,151 - $100,525 | $94,301 - $201,050 |
| 24% | $100,526 - $191,950 | $201,051 - $383,900 |
| 32% | $191,951 - $243,725 | $383,901 - $487,450 |
| 35% | $243,726 - $609,350 | $487,451 - $731,200 |
| 37% | $609,351+ | $731,201+ |
Marginal vs. Effective Tax Rate
Marginal rate: The rate on your next dollar of income. Effective rate: Your actual overall tax rate (total tax ÷ total income).
Example: Single filer earning $85,000
| Bracket | Income in Bracket | Tax | Rate |
|---|---|---|---|
| 10% | $11,600 | $1,160 | 10% |
| 12% | $35,550 | $4,266 | 12% |
| 22% | $37,850 | $8,327 | 22% |
| Total | $85,000 | $13,753 |
- Marginal rate: 22%
- Effective rate: $13,753 ÷ $85,000 = 16.2%
Common misconception: "If I earn more, I'll move into a higher bracket and take home less." Wrong. Only the income in the new bracket gets taxed at the higher rate. A raise always increases your take-home pay.
Beyond Federal Income Tax
Federal income tax is just one piece. Your total tax burden includes:
| Tax | Rate/Amount | Notes |
|---|---|---|
| Federal income tax | 10-37% (progressive) | Largest piece for most |
| Social Security (FICA) | 6.2% (up to $168,600) | Employer pays matching 6.2% |
| Medicare | 1.45% (no cap) | +0.9% over $200k single/$250k joint |
| State income tax | 0-13.3% | Varies by state (7 states have no income tax) |
| Local income tax | 0-4% | Some cities/counties |
| Capital gains | 0/15/20% | Long-term (held >1 year) |
| Net Investment Income Tax | 3.8% | Above $200k single/$250k joint |
Total effective rate for a median earner: Roughly 25-35% when combining all taxes.
Deductions vs. Credits
These are different, and the difference matters enormously.
Tax Deductions
Reduce your taxable income. The value depends on your bracket.
$1,000 deduction at 22% bracket = $220 tax savings
$1,000 deduction at 32% bracket = $320 tax savings
Tax Credits
Reduce your tax bill directly. Dollar for dollar.
$1,000 credit = $1,000 tax savings (regardless of bracket)
Credits are always more valuable than deductions of the same amount.
Refundable vs. Non-Refundable Credits
| Type | What Happens | Examples |
|---|---|---|
| Non-refundable | Reduces tax to $0 but no further | Child and Dependent Care Credit |
| Refundable | Can create a refund below $0 | Earned Income Tax Credit (EITC) |
| Partially refundable | Refundable up to a limit | Child Tax Credit ($1,700 refundable portion) |
Standard vs. Itemized Deductions
You choose one. Most people take the standard deduction since 2018 (Tax Cuts and Jobs Act).
Standard Deduction (2024)
| Filing Status | Amount |
|---|---|
| Single | $14,600 |
| Married Filing Jointly | $29,200 |
| Head of Household | $21,900 |
| Additional (age 65+ or blind) | $1,550-1,950 |
Common Itemized Deductions
Only itemize if your total exceeds the standard deduction:
| Deduction | Limit | Notes |
|---|---|---|
| State and local taxes (SALT) | $10,000 cap | Property + income/sales tax |
| Mortgage interest | On first $750,000 of debt | Primary + secondary home |
| Charitable contributions | 60% of AGI (cash) | Must itemize; need receipts |
| Medical expenses | Above 7.5% of AGI | Only the excess |
| Casualty/theft losses | Federally declared disasters only | Very limited |
Who typically itemizes: Homeowners in high-tax states with large mortgages and significant charitable giving. Everyone else takes the standard deduction.
"Above the Line" Deductions
These reduce AGI regardless of whether you itemize. Take these in addition to the standard deduction.
| Deduction | Maximum | Who Qualifies |
|---|---|---|
| HSA contributions | $4,150/$8,300 | Those with qualifying HDHP |
| Traditional IRA | $7,000 ($8,000 if 50+) | Income limits apply if covered by employer plan |
| Student loan interest | $2,500 | Income limits apply |
| Self-employment tax (50%) | Half of SE tax | Self-employed |
| Self-employed health insurance | Premium amount | Self-employed |
| Educator expenses | $300 | K-12 teachers |
Tax-Advantaged Accounts Overview
These are the most powerful legal tax reduction tools available. For full details, see investing/03-tax-advantaged.
| Account | Tax Benefit | 2024 Limit |
|---|---|---|
| Traditional 401k | Deduct now, tax on withdrawal | $23,000 (+$7,500 catch-up) |
| Roth 401k | No deduction, tax-free withdrawal | $23,000 (+$7,500 catch-up) |
| Traditional IRA | May deduct now, tax on withdrawal | $7,000 (+$1,000 catch-up) |
| Roth IRA | No deduction, tax-free growth/withdrawal | $7,000 (+$1,000 catch-up) |
| HSA | Deduct now, tax-free growth, tax-free withdrawal for medical | $4,150/$8,300 |
| 529 Plan | State deduction (varies), tax-free growth for education | Varies by state |
| FSA | Pre-tax for medical/dependent care | $3,200 (medical) / $5,000 (dependent) |
HSA is the only triple-tax-advantaged account. Max it if you can.
Traditional vs. Roth: When Each Wins
| Factor | Traditional (Pre-Tax) | Roth (Post-Tax) |
|---|---|---|
| Tax rate now vs. later | Higher now, lower later | Lower now, higher later |
| Early career | Less beneficial | More beneficial |
| Peak earning years | More beneficial | Less beneficial |
| Retirement | Taxed as income | Tax-free |
| RMDs | Required at 73 | None (Roth IRA) |
Simple rule: If your tax rate is lower now than it will be in retirement, choose Roth. If higher now, choose Traditional. When in doubt, split between both (tax diversification).
Common Tax Credits
| Credit | Amount | Who Qualifies |
|---|---|---|
| Child Tax Credit | $2,000 per child under 17 | Income limits: phases out $200k single/$400k joint |
| Earned Income Tax Credit | Up to $7,430 (3+ children) | Low-to-moderate income workers |
| American Opportunity Credit | Up to $2,500/year (4 years) | First 4 years of college |
| Lifetime Learning Credit | Up to $2,000/year | Education expenses (no limit on years) |
| Saver's Credit | Up to $1,000/$2,000 | Low-income retirement savers |
| Energy Efficient Home Credit | Up to $3,200/year | Solar, heat pumps, insulation, etc. |
| EV Tax Credit | Up to $7,500 | New qualifying electric vehicles |
| Child and Dependent Care | Up to $2,100 | Childcare for kids under 13 |
Check every credit you might qualify for. Many people miss credits they're eligible for.
Quarterly Estimated Taxes
Who Needs to Pay
If you'll owe $1,000+ in tax at filing (after withholding and credits), you need to make quarterly payments. Common for:
- Self-employed/freelancers
- Side hustlers with significant income
- Investors with large capital gains
- Retirees without sufficient withholding
Due Dates
| Quarter | Period Covered | Due Date |
|---|---|---|
| Q1 | Jan 1 - Mar 31 | April 15 |
| Q2 | Apr 1 - May 31 | June 15 |
| Q3 | Jun 1 - Aug 31 | September 15 |
| Q4 | Sep 1 - Dec 31 | January 15 (next year) |
Safe Harbor Rules
Avoid underpayment penalties by paying at least:
- 90% of current year's tax, OR
- 100% of prior year's tax (110% if AGI > $150,000)
Easiest approach: Pay 100% (or 110%) of last year's tax divided into four payments. Settle up at filing.
How to Pay
- IRS Direct Pay (irs.gov/payments)
- EFTPS (Electronic Federal Tax Payment System)
- IRS2Go app
- Credit card (with processing fee, usually not worth it)
Tax Planning Strategies
Timing Income and Deductions
| Strategy | How It Works | When to Use |
|---|---|---|
| Defer income | Push income to next year | Expect lower bracket next year |
| Accelerate deductions | Pull deductions into this year | Higher bracket this year |
| Bunch charitable giving | Give every other year to exceed standard deduction | Alternate itemizing/standard |
| Donor-advised fund | Contribute a lump sum, distribute over time | Large charitable giving |
| Tax-loss harvesting | Sell losing investments to offset gains | Taxable investment accounts |
| Roth conversion | Convert Traditional to Roth in low-income years | Sabbatical, early retirement, gap year |
Salary Employee Strategies
- Max out 401k. $23,000 tax-deferred
- Max out HSA. $4,150/$8,300 triple-tax-free
- Contribute to IRA. $7,000 (deduction depends on income/plan coverage)
- Use FSA. $3,200 for medical, $5,000 for dependent care (pre-tax)
- Check withholding. Aim for roughly break-even at filing (not a big refund)
A big tax refund is not a win. It means you gave the government an interest-free loan. Adjust W-4 so you roughly break even.
Self-Employed Strategies
| Strategy | Benefit |
|---|---|
| Solo 401k | Up to $69,000 in contributions (2024) |
| SEP IRA | Up to 25% of net self-employment income |
| Deduct business expenses | Home office, equipment, software, travel, meals (50%) |
| Deduct self-employment tax (50%) | Above-the-line deduction |
| Deduct health insurance premiums | Above-the-line for SE individuals |
| Choose entity type | S-Corp can reduce self-employment tax |
| Retirement plan contributions | Reduces both income tax and SE tax |
When to Hire a CPA
Do It Yourself If
- W-2 income only
- Standard deduction
- Simple investment income
- No self-employment
- No major life changes
Tools: TurboTax, FreeTaxUSA, H&R Block, IRS Free File (income < $79,000)
Hire a Professional If
- Self-employed or own a business
- Rental property income
- Complex investment situations (stock options, RSUs)
- Major life events (marriage, divorce, inheritance)
- Multi-state income
- Income over $200,000 with complex deductions
- You received an audit notice
- You're unsure if you're missing deductions/credits
Cost: $200-500 for a standard return. $500-2,000+ for complex situations. Often pays for itself in found deductions.
Types of Tax Professionals
| Type | Credentials | Best For |
|---|---|---|
| CPA | Licensed, exam-passed, continuing education | Complex situations, audit representation |
| Enrolled Agent (EA) | IRS-licensed, tax specialist | Tax-specific issues, audit representation |
| Tax attorney | Law degree, bar admission | Legal disputes, IRS problems |
| Tax preparer (PTIN) | Basic registration only | Simple returns (be careful) |
Avoid: Chain tax shops that hire seasonal workers with minimal training. Find a CPA or EA through referrals.
Audit Triggers
| Trigger | Why |
|---|---|
| High income (>$500k) | Higher audit rate for high earners |
| Large charitable deductions | Relative to income |
| Home office deduction | Historically abused |
| Cash-heavy business | Hard for IRS to verify |
| Round numbers everywhere | Looks estimated, not actual |
| Excessive business expenses | Entertainment, travel, meals |
| Not reporting all income | IRS has copies of your 1099s |
| Large Schedule C losses | Especially repeated losses |
| Earned Income Tax Credit | High error rate on this credit |
| Foreign accounts/income | FBAR and FATCA reporting |
If You're Audited
- Don't panic: most audits are mail audits (correspondence)
- Respond by the deadline
- Provide only what's asked for (no more)
- Have documentation for every deduction
- Consider hiring a CPA or EA to represent you
- You have appeal rights if you disagree
Best audit protection: Keep good records. Save receipts, statements, and documentation for at least 3 years (7 years for some items).
Key Tax Dates
| Date | What |
|---|---|
| January 15 | Q4 estimated tax due |
| January 31 | Employers send W-2s; 1099s issued |
| April 15 | Tax filing deadline; Q1 estimated tax due |
| April 15 | IRA/HSA contribution deadline for prior year |
| June 15 | Q2 estimated tax due |
| September 15 | Q3 estimated tax due |
| October 15 | Extended filing deadline |
| December 31 | 401k contribution deadline; tax-loss harvesting deadline |
Key Takeaways
- Understand marginal rates. A raise never makes you take home less
- Credits beat deductions. Dollar for dollar vs. bracket-dependent
- Max tax-advantaged accounts. 401k, IRA, HSA are your best tools
- Don't overpay withholding. A big refund is an interest-free loan to the IRS
- Keep records. Receipts, statements, and documentation for 3-7 years
- Self-employed: plan quarterly. Estimated payments avoid penalties
- Hire help when it's complex. A good CPA pays for themselves
- Tax planning is year-round, not just April