What happens if 2 people file the same thing(head of household)using the same address accidentally??

[JamesG1]

To qualify for Head of Household filing status, you must pay more than half of the cost of keeping up a home for the year.  These costs include:

• Rent,
• Mortgage interest,
• Real estate taxes,
• Homeowner insurance,
• Repairs or maintenance,
• Utilities,
• Food eaten in the home,
• Household expenses.

You assume that the IRS would question the two taxpayers as to whether they can prove that they each paid more than half of the cost of their household.

It is possible to imagine two households sharing one common address where each household pays its own bills and supports its own qualifying child.  This help addresses that rare situation.