The deadline to file your 2020 income tax return has passed, but it's not too late to claim the unpaid portion of your stimulus check: You only have to file your tax return anyway.

The Treasury Department has already distributed nearly 165 million individuals and households with stimulus checks3 ($1,400 in direct payments under the Biden Administration's "American Rescue Plan") for a total of over $388 billion in relief. [This is additional funding for those who received their third stimulus check earlier this spring (before filing their 2020 tax returns) but who qualify for additional payments based on their 2020 income. This is additional funding for those who received their third stimulus check in early spring (prior to filing their 2020 tax returns), but who qualify for additional payments based on their 2020 income.

The IRS is also sending checks to eligible individuals whose tax information was not previously on file as soon as the IRS processes their returns. These include persons with no permanent address and those with little or no income.

However, some people may still be eligible for more stimulus: those whose 2020 income is less than their 2019 income can use the Recovery Rebate Credit on Form 1040 or Form 1040-SR, line 30, to receive stimulus checks 1 and 2 to claim additional funds totaling $1,200 and $600, respectively.

If you have already filed a tax return and have not filed this application but believe you qualify for the Recovery Rebate Credit, you may file an amended return.

According to CNBC, Americans have until October 15, the extended filing deadline, to file the deficiency. Additionally, tax refunds (like the special reconstruction credit) can usually be claimed for up to three years after the official deadline.

Bottom line: if you still have stimulus tax breaks remaining, file a return or amend one already filed.

According to the Boston Herald, more than 1 million Americans failed to cash in the first round of stimulus payments provided by the March 2020 CARES Act. The IRS states that this figure includes funds that were paid back or left uncashed.

The Herald did not specify who received these payments, but some of these checks may have gone to people who moved without leaving a forwarding address or who died after filing their 2018 tax returns.

The uncashed checks represent less than 1% of the estimated 130 million stimulus checks provided by the CARES Act, but they may become a talking point for politicians and pundits who oppose the fourth round of the stimulus package.