You can not find out from the IRS. The IRS is prevented by privacy laws from revealing such information
No ethical tax preparer will tell you anything about another person's tax return.
You are correct, if you are assuming that only one person in a household can claim HoH.
It's theoretically possible for two to be HoH; but from a practical application, is not. The rule is that you must have paid more than half the household expenses. If you paid more than half, the other person must have paid less than half.
If your situation closely matches the IRS "Acknowledged Significant Advice" at the link below, you probably qualify. <a rel="nofollow" target="_blank" href="http://www.unclefed.com/ForTaxProfs/irs-wd/1998/1998-041.pdf">http://www.unclefed.com/ForTaxProfs/irs-wd/1998/1998-041.pdf</a> . It's a tough standard to meet and most living arrangements will not qualify. If you try it, be prepared to prove it with detailed accounting records of household expenses.
If you qualify to claim HOH, go ahead and do so. If someone else does well, the IRS will contact both of you and sort it out.
Be aware that if two taxpayers file HOH for the same address you can be sure that both will receive a from 886-H-HOH to fill out within a year or two after filing. That form requires that you supply all of the documentation to support your claim.
<a rel="nofollow" target="_blank" href="https://www.google.com/search?q=form+886-h-hoh&ie=utf-8&oe=utf-8">https://www.google.com/search?q=form+886-h-hoh&ie=utf-8&oe=utf-8</a>
You can not do anything except file a correct tax return. If someone else that is not qualified to do so also files as Head of Household at your residence, the IRS will intervene. However, you can't and should not worry about what the other person does. As long as you are filing a accurate tax return, you should have zero issues when claiming your refund.
You can qualify for Head of Household if you:
If you were still legally married as of December 31, 2019 and a child lives with you, you can qualify for Head of Household under a slightly different set of rules. Read more
After you answer all the questions about yourself and your dependents at the beginning of your return, we'll let you know if your situation qualifies for Head of Household.
You can also revisit these questions by selecting My Info (online) or Personal Info (software), and then selecting Edit next to your name or your dependent's.
Related Information: