This takes affect with in 30 days of when the offset paperwork is placed in the IRS system. however because of processing times of the refunds themselves and work loand, the actual transfer of money can take as long as 18 weeks to reach the mother.
By the way, you can ask the IRS to allocate the refund from your joint return, so that your portion of the refunds are not used for child support. You do this by submitting the following form:
This will get smaller eventually, but remember, it can take as long as 18 weeks to reach the recipient, and once she is paid, the HHS and child enforcement can then take penalties, interest, and administration charges. So, he may have at least one or two more lesser offsets.