I think IRS writes off any balance owed of $5 or less, but it's been so long since I have thought that, I couldn't tell you the source. 

Meanwhile, I did a 2021 return for the PR of a deceased nonfiler.  Filed it a couple months before the statute expired in April 2025.  Filed 2022, 2023 and 2024 returns a few weeks later, and those refunds were issued promptly.  For 2021, IRS sent a notice saying that nothing would be paid until the decedent called to verify his identity.  In May I asked the Austin SC Taxpayer Advocate to look into it, and last week the check was received.