Tax filing season is underway.

Most Americans should be able to file their 2021 tax returns to the IRS for free.

About 100 million Americans, or roughly 70% of people filing taxes in the U.S., are eligible to submit their tax returns to the IRS at no cost, according to the agency. Even more Americans may be able to submit their 2021 tax returns at little or no cost through other tax-preparation programs.

There are also other underused services that can help people this tax season, said Tania Brown, a certified financial planner based in Atlanta and financial coach at SaverLife, a nonprofit focused on financial security.

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"There are free options; they do not necessarily have to pay to get their taxes done," she said.

Here's what you need to know about filing for free. 

IRS Free File program

Many Americans are eligible to file their taxes for free through the IRS Free File program, which is a public-private partnership between the agency and the Free File Alliance, a group of tax preparation companies with online software such as TaxAct, FreeTaxUSA and others.

In 2020, 4.2 million Americans used the Free File program for their 2019 taxes, according to the IRS. While that was a nearly 50% increase from the previous year, more could still use the program.

If your adjusted gross income in 2021 was less than or equal to $73,000, you can use one of the Free File software programs to submit federal taxes free of cost. In addition, some products will also let you file your state taxes for free. The software generally includes step-by-step instructions and help for filers.

This year it may be especially important for Americans to use the service, as it will help them file electronically. The IRS has recommended that people file online and receive any refunds through direct deposit this year to avoid delays.

To use the program, you must go through the IRS site — not directly to a tax preparer. The program opened Jan. 14.

There are also free basic tax preparation services offered through the IRS Volunteer Income Tax Assistance and Tax Counseling for the Elderly programs, called VITA and TCE, respectively.

VITA and TCE cater to low-income filers who generally make $58,000 or less, people with disabilities, limited English speakers and those over 60 years old. Tax experts volunteer their time to help eligible people prepare and file tax returns.

These options were generally held in-person pre-pandemic, but many will operate differently this year. Some sites have been closed due to the crisis, some will do the program online and others may be in person. To find a VITA or TCE center, use the IRS locator tool.

What to do if you made more than $73,000

If your gross adjusted income was more than $73,000 in 2021, there is another free program that you can access through the IRS, but it requires you to prepare your taxes yourself.

The Free Fillable Forms program offers online tax forms that people can use to input their information and then either electronically file with the IRS or print out and mail to the agency.

Unlike other programs, Free Fillable Forms doesn't give you any guidance or step-by-step instruction — it only does basic calculations of the numbers you put into the forms. It's also only available for federal taxes — though people in certain states can access local programs to file their state returns.

Still, if you have the time and are comfortable preparing your own taxes, the Free Fillable Forms program is a good option.

Other free services

There are also some private companies that offer tax filing services at no cost, such as TurboTax, owned by Intuit; H&R Block; TaxAct; and Credit Karma.

These companies all have free filing options available to some, depending on their annual income, the simplicity of the return, where they live, military status, eligibility for certain credits and more.

Before using online software outside the IRS Free File program, check with the company to see if you're eligible to file for free and make sure you're using the correct product, instead of one that will charge you.

Credit Karma is free for all filers regardless of income and includes federal and state returns, according to the company. Customers also have access to support staff able to answer any questions they have, Credit Karma said.

When to pay for help

To be sure, some people may still want to pay for help in filing their taxes because they don't qualify for a free program or don't want to spend the time to do their own taxes. There are many online software programs that help people file for a fee, and have products serving a wide range of tax scenarios at different price points.

If you have a more complicated return, such as you itemize deductions, are a sole proprietor with income or run a small business, you may want to get help via a software program or hire an accountant or other tax expert to help you file.

This year, filing an accurate return is important to avoid delays in getting any refund you're owed.

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