Tax day is approaching, and it will soon be time to begin assembling forms. If you haven't looked at them yet, all those numbers and letters – W-2, W-9, 1099 – can quickly overwhelm you.

Some forms are pre-populated and designed for you to pass on to the IRS. They may be headed to your mailbox or sitting in a "tax documents" portal on a website, awaiting download. In theory, there may be nothing you need to do apart from delivering them to your tax preparer, if you have one, or documenting appropriate sums on your tax return. Other forms will require some action on your part.

More: Tax season can be terrifying. Here's everything to know before filing your taxes in 2024.

Here is a rundown.

What is a W-9 used for?

A W-9 is typically used by businesses to collect a person's identifying information, such as a Social Security number or tax identification number.

A typical reason for filling out a W-9 is that you're an independent contractor, freelancer or gig worker likely to earn more than $600. You may also be asked to fill out a W-9 when you open an interest-bearing bank account or another financial account that delivers extra income.

This form doesn't go to the Internal Revenue Service. But the information you provide on a W-9 will be used to prepare and populate other forms: Read on.

Is a W-9 the same as a 1099?

The main difference between a W-9 and a 1099 is that you fill out a W-9, while the business or entity that is paying you fills out the 1099. In most cases, you should receive any 1099 form by the end of January.

A 1099 form is used to report income that isn't directly earned through an employer. Because there are many different ways to make money outside of a traditional job, there are several types of 1099 forms.

Common 1099s you might see: 1099-G, 1099-K, 1099-R, 1099-Div

Some of the most common 1099s you may receive:

• 1099-G: details any state or local tax refund that's considered income.

• 1099-K: summarizes any income you earned, if you made at least $20,000 and had more than 200 transactions on a third-party payment network like Etsy, Airbnb or Venmo.

• 1099-R: reports distributions of $10 or more from various types of retirement plans, annuities, pensions, insurance contracts, and similar accounts.

• 1099-Div: used by banks and other financial institutions to report dividends and other distributions to taxpayers and to the IRS.

What is a W-4, and what is it for?

A W-4 is a form you're required to fill out when you work directly for an employer.

It tells your employer how much federal income tax should be withheld from your paycheck based on factors like whether you're married and filing a joint return, whether you have dependents to claim, and whether you work multiple jobs.