If the child was born in 2018, you probably qualify for significant tax benefits by claiming her as a dependent. But there is no law that says you must claim her. (Claim her and send me the $2000 if you don’t want it.)
However, it is the law that she must have a valid SSN when you file an “on time” tax return claiming her as a dependent to get these benefits. If you file now without her SSN, and then amend later to claim her, no credits or deductions will be paid.
An on time tax return is one that is filed by April 15, or by October 15 if you previously requested an extension before April 15. If you do plan to claim her as a dependent, wait until you get the SSN, even if it means filing an extension.
If the child is in the midst of an adoption, you can get a temporary adoption tax number that does the same thing. If the child is not a US citizen and not eligible for an SSN, you can apply for an ITIN that will allow you to claim her as a dependent although with reduced credits.
Thank you for the quick answer. Curiously, when I claim her as a dependent, I don't get any additional refund, at least according to the TurboTax tally at the top left corner of the site. However, I live overseas and do not have to pay taxes on my income here—and I have no US income—so maybe that's what's making this strange. Does that seem correct?
For the question, how long did she live with you, you need to answer “all year”. That is the correct answer for a newborn who has lived with you since birth. You may also have to enter a fake SSN to get the credits to calculate.
It’s also possible you don’t get a benefit in your situation, but I’m not as familiar with international tax issues.
Ah, OK, thanks for the "all year" tip. In fact, now my refund is smaller when I claim her as a dependent! I (more or less) trust the TurboTax software, and I believe I entered everything correctly, so I think there is something weird about living overseas, and having no liability on income, that is messing this up. So I think I will just leave her off. Thanks again for the help.