Head of household question

For Head of Household filing status they have to provide over on-half the cost to maintain the home.  If that is all she is contributing to the household then she cannot have HOH status and would file as Single if not legally married.

 

See this TurboTax support FAQ for HOH - https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-filing-status/qualify-head-household-2021/L0NxUtVc2_US_en_US?uid=la01tm4f

assuming she's not legally married, you can claim your grandson but not your daughter as a dependent. 

since your daughter works her income probably disqualifies her from being claimed by anyone as a dependent.

if the same situation applied in 2019 and 2020 you can go back to amend those returns to claim HOH. 

if you file as HOH for any year where your daughter claimed it, realize she is going to get a tax bill. she'll lose the preferential tax rate and certain credits. however, it was improper for her to claim HOH for the last 6 years because apparently, she did not provide 50% of her son's support  

Under your facts, your daughter cannot claim head of household status.

 

She could file as single and claim her child as a dependent, and you will also file as single (unless you have a spouse you didn’t mention).

 

Or, if you are single and you have more taxable income than your daughter, you could claim your grandchild as a dependent and file head of household, and your daughter would file single with no dependents.  

You cannot claim Head of Household (HoH), on your tax return, unless you have a dependent.  

As others have said, when a child lives with a parent and grandparent, it's optional which one of you claims the  child as a dependent (and for HoH). There are 2 caveats:

1. If you can't agree on who will claim the child, then the parent has first rights

2. The grandparent must have a higher income (AGI) than the parent

 

.A child closely related to a taxpayer can be a “Qualifying Child (QC)” dependent, regardless of the child's income, if:

1. He is under age 19, or under 24 if a full time student for at least 5 months of the year, or  is totally & permanently disabled
2. He did not provide more than 1/2 his own support
3. He lived with the relative (including temporary absences) for more than half the year
4. He is younger than the relative (not applicable for a disabled child)
5. If the child meets the rules to be a qualifying child of more than one person, you must be the person entitled to claim the child as a qualifying child (this essentially means that you have the parent’s permission to claim the child, if the child also lived with the parent more than half the year)
6. If the parents of a child can claim the child as a qualifying child but no parent so claims the child, no one else can claim the child as a qualifying child unless that person's adjusted gross income (AGI) is higher than the highest AGI of any of the child's parents who can claim the child.

See full dependent rules at: https://turbotax.intuit.com/tax-tools/tax-tips/Family/Rules-for-Claiming-a-Dependent-on-Your-Tax-Return/INF12139.html