When it comes to taxes, the first thing to understand is that not every dollar you earn is actually taxed. The government is only interested in your taxable income.

Think of all the money you make in a year from all sources—your job, a side hustle, investments. This is your gross income. But you don't pay tax on that whole amount. Instead, you get to subtract certain things, like deductions, to lower this number. What's left over is your taxable income. This is the figure the IRS uses to calculate how much tax you owe.

We'll explore deductions in more detail later, but for now, just remember that your taxable income is always less than your gross income. It’s the number that truly matters for your tax bill.

The United States uses a progressive tax system. This means that as your income increases, the tax rate you pay also increases. People with higher incomes pay a larger percentage of their income in taxes than people with lower incomes.

This is different from a flat tax, where everyone pays the same percentage, regardless of how much they earn. The progressive system is built on the idea that those who can afford to pay more should contribute a larger share.

This is where the concept of tax brackets comes in. Your income isn't taxed at a single rate. Instead, it's divided into different levels, or “brackets,” and each bracket is taxed at a progressively higher rate.

In the U.S., you'll likely deal with two main types of income tax: federal and state.

Federal income tax is collected by the national government through the Internal Revenue Service (IRS). This money funds everything from national defense and Social Security to scientific research and national parks.

State income tax is collected by the state you live in. These funds are used for state-level services like public schools, state highways, and local law enforcement. Tax rules vary significantly from one state to another.

This is one of the most misunderstood parts of taxes. Many people think if they're “in” a certain tax bracket, all their income is taxed at that rate. That's not how it works.

Your income fills up the tax brackets one by one, from the lowest rate to the highest. Everyone pays the same low rate on their first chunk of income. You only pay the higher rates on the money that falls into those higher brackets.

Let’s look at a simplified example. Imagine the tax brackets are: • 10% on income up to $10,000 • 20% on income from $10,001 to $40,000 • 30% on income over $40,000

If your taxable income is $50,000, your tax isn't a flat 30% of $50,000. Here's how it's calculated:

Your total tax is $10,000. Even though your top income falls into the 30% bracket, your effective tax rate is actually 20% ($10,000 tax / $50,000 income). Your highest tax rate, 30%, is called your marginal tax rate. This is the rate you would pay on one additional dollar of income.

This tiered system ensures that earning more money always means taking home more money. You can never lose money by moving into a higher tax bracket.