How to prevent owing taxes on 2021 return after receiving the child tax credit throughout 2021?

Hello,

 

My family started receiving $300 for each of our 2 children ($600 total) this month, July 2021. It's my understanding that this monthly amount is essentially a payment spread throughout the year of the dependent tax credit we would have received after filing out 2021 tax return. Is this a correct understanding? Also, what are some of the risk factors that would make us owe 2021 taxes now that we won't be able to deduct our dependents at the end of the year as we usually did in the past?