if the IRS sent you a notice asking for proof you are entitled to claim the dependents then the notice also lists documents and ways that can be used to prove you are entitled to claim them. read the notice and respond in a timely manner otherwise, the next notice you get will be a bill because the IRS will disallow your claim and also switch your filing status from head of household to single.
also, make sure that the dependents are either qualifying children or qualifying relatives
you can claim him/her as a qualifying child if all these tests are met
• he/she has the same principal abode as you for more than ½ the tax year. Temporary absences like for school are ignored
• if he/she is not a full-time student, he's/she's under 19 at the end of the tax year. If a full-time student, he's/she's under 24 at the end of the tax year.
• he/she hasn't provided over ½ his/her own support
• he/she didn't file a joint return unless there was no tax liability but merely filing jointly to facilitate refund of taxes withheld or estimates paid
or you can claim him/her as a qualifying relative if all these tests are met
• his/her gross income for 2020 less than $4,300
• you provided over ½ his/her support
• he/she isn't a qualifying child of another taxpayer
