With rent, food prices, and utility bills up, many families could use some extra cash. Inflation is stressing people’s budgets big time.

If you’re struggling and didn’t file a tax return this year, check your mail.

Last week, the IRS started sending letters to the 9 million households that may still be eligible for several lucrative tax benefits, including the third round of stimulus payments, worth as much as $1,400 for an individual and $2,800 for couples.

If you didn’t get the full amount of the pandemic-related Economic Impact Payment under the $1.9 trillion American Rescue Plan, you may be able to claim the 2021 credit. But you must submit a 2021 tax return -- even if you don’t usually file taxes. The payments were the largest of those sent to Americans under federal coronavirus relief packages starting in 2020.

You don’t have to have income for 2021 to qualify for the stimulus money. But there are income caps.

The IRS faced a daunting task amid the pandemic to reach millions of people who don’t typically file tax returns. Technically, the stimulus payments were an advance of a credit referred to on Forms 1040 and 1040-SR as the Recovery Rebate Credit.

For the third round of payments, eligible individuals with an adjusted gross income (AGI) of $75,000 or less were entitled to the full $1,400. The ceiling was $112,500 for individuals filing as head of household and $150,000 for couples filing jointly. Your AGI is your gross income minus certain adjustments.

Eligible taxpayers could also claim a whopping $1,400 for each dependent. The relief was expanded to include older dependents, such as dependent college students, disabled adult children or a parent you support.

In addition to the stimulus payments, households that file a 2021 return also may be eligible for the expanded child tax credit and the earned-income tax credit. For those without children, the American Rescue Plan nearly tripled the earned-income tax credit from $543 to $1,502. The credit can be as much as $3,618 for those with one child, $5,980 for those with two children and $6,728 for those with at least three children.

The child tax credit was increased to $3,600 for children 5 and younger and $3,000 for those 6 through 17. The credit wasn’t new; it was created in 1997 and has always been meant to help struggling families. What was different for the 2021 tax year was the boost from the pre-pandemic maximum of $2,000 per child younger than 17.

“For 2021, for the first time, families can get the child tax credit, even if they owe no tax and even if they don’t have a job or business,’’ said IRS spokesman Eric Smith.

The IRS specifically urged grandparents, foster parents, and people caring for siblings or other relatives to check their eligibility for the 2021 child tax credit.

The Child and Dependent Care Credit (this is different from the child tax credit) also was expanded, making more people eligible and increasing the total credit to $4,000 for one qualifying individual and $8,000 for two or more.

The IRS letters will be arriving in mailboxes this month to people who appear to qualify for the credits but haven’t yet filed a 2021 return. The Treasury Department’s Office of Tax Analysis identified individuals who typically are not required to file a tax return because they appear to have very low incomes, based on W-2s, 1099s, and other third-party statements, according to the IRS.

“This mailing was designed to reach people who didn’t file and mostly have modest incomes,’’ Smith said.

To help people file their returns to claim the credit, the IRS said, the agency’s Free File program at irs.gov will remain open for an extra month, until Nov. 17 at midnight, Eastern time. The fastest way to file a return and claim these credits is to file electronically. People whose incomes are $73,000 or less can use Free File using brand-name software.

The IRS said people who aren’t required to file a 2021 tax return - usually individuals earning less than $12,500 or $25,000 for married couples - can also visit childtaxcredit.gov/file to submit a simple 2021 income tax return.

If you miss the electronic filing period, you can still claim the credits by filing a paper return, though it may take some time for the IRS to get to it. There’s still a significant backlog of paper returns. You can find tax forms by going to irs.gov/forms or calling 800-TAX-FORM (800-829-3676).

Throughout the pandemic, the IRS, and the Treasury Department have struggled to get COVID-related money to some people, especially those with lower incomes, with limited Internet access or experiencing homelessness, according to a recent blog post by the Government Accountability Office.

This latest effort by those agencies to track down families is much needed for those who could certainly use an infusion of cash as they struggle with rising consumer prices.

Michelle Singletary can be reached at michelle.singletary@washpost.com.