You should be able to handle this by replying to the notice.
OTHERWISE,
After entering on 1040-X Col A the IRS-adjusted amount that reduces your refund or make you owe,
enter in Col C the amount you had in the first place.
In Explanation, state you are reinstating your dependent with their correct Social Security Number.
You must list all dependents.
The amount on Line 18 will depend on your decision whether or not to pay any amount the IRS is asking for now.
IRS processing time for 1040-X is currently about ten months.
@caaintuit
