(NEXSTAR) — If you receive a letter from the Internal Revenue Service don’t panic, it could mean there is money waiting to be claimed.

The IRS announced in mid-October that it is trying to contact over 9 million people who are still owed stimulus payments, the Earned Income Tax Credit, or the Child Tax Credit.

“The IRS wants to remind potentially eligible people, especially families, that they may qualify for these valuable tax credits,” said IRS Commissioner Chuck Rettig. “We encourage people who haven’t filed a tax return yet for 2021 to review these options. Even if they aren’t required to file a tax return, they may still qualify for several important credits. We don’t want people to overlook these tax credits, and the letters will remind people of their potential eligibility and steps they can take.”

The IRS is keeping its free filing tool open for an extra month this year, extending the deadline to Nov. 17. You can also use ChildTaxCredit.gov to file a 2021 tax return and claim the credit – even if you don’t have children.

The easy file tool streamlines the process, especially for people who don’t usually file, but people who miss the November deadline can still file a 2021 tax return. Typically there is a three-year period for tax filers to claim credits they are eligible for, according to CNBC.

Why didn’t so many people initially get the IRS payments?

Many of those people didn’t initially get their payments because the IRS didn’t have their information on file from a recent tax return. People with very little or no income, for instance, aren’t required to pay taxes.

“Throughout the pandemic, IRS and Treasury struggled to get COVID-relief payments into the hands of some people — especially those with lower incomes, limited internet access, or experiencing homelessness,” the Government Accountability Office, an internal government watchdog, said.

What benefits are included?

Child Tax Credit: Families can claim this credit, even if they received monthly advance payments during the last half of 2021. The total credit can be as much as $3,600 per child.

Earned Income Tax Credit: The EITC helps low- to moderate-income workers and families get a tax break. The American Rescue Plan boosted the EITC, increasing the amount childless workers can receive to $1,502. The credit is $3,618 for workers with one child, $5,980 for those with two children and $6,728 for those with at least three children.

Recovery Rebate Credit: The third so-called stimulus check is $1,400 for each qualifying adult, plus $1,400 for each eligible child or adult dependent. For married couples, the qualifying income level is $150,000 or less, $75,000 or less for single taxpayers and $112,500 or less if filing as head of household. The credit is phased out above those thresholds.

The IRS recommends that people owed either of the three benefits file electronically to get the money as fast as possible.