In general, you cannot make a claim for the same dependent if someone else (typically the other parent) is claiming an amount on Line 30400 of their return. A child can only be claimed as a dependant by one parent.
-> You cannot claim any amount from this dependant.
-> You do not need to enter dependant on the other spouse's return.
However, the amount for an Eligible Dependant Credit is a non-refundable tax credit for single adults who are responsible for the financial care of a relative and are not claiming the Spouse/common-law partner Credit. If that spouse has already claimed their spousal amount, they cannot claim the eligible dependant amount for the child. In addition, they cannot also claim the Canada Caregiver Amount For Child if the child is infirm and under 18 years old.
There are some exceptions to eligibility you should pay attention to.
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