Did you see the "some exceptions to this rule" ? A child who is born or died during the year is treated as if they lived the entire year. https://www.irs.gov/pub/irs-pdf/p17.pdf
Death or birth of child. A child who was born
or died during the year is treated as having lived
with you more than half of the year if your home
was the child's home more than half of the time
he or she was alive during the year. The same
is true if the child lived with you more than half
the year except for any required hospital stay
following birth.
Child born alive. You may be able to claim
as a dependent a child born alive during the
year, even if the child lived only for a moment.
State or local law must treat the child as having
been born alive. There must be proof of a live
birth shown by an official document, such as a
birth certificate. The child must be your qualifying child or qualifying relative, and all the other
tests to claim the child as a dependent must be
met.
And the other rule about support ... for a qualifying child it reads that "the child cannot provide more than 1/2 of their own support" ... the parents don't have to pay a thing. Support comes into play for HOH filing status and Qualified Relatives.
Support Test (To Be a Qualifying
Child)
To meet this test, the child can’t have provided
more than half of his or her own support for the
year.
This test is different from the support test to
be a qualifying relative, which is described later.
