Can an plan administrators' QMCSO procedures provide that a QMCSO will not be honored if the QMCSO is not submitted to the plan administrator within 31 days of the date of the order?

25 USC §1169(a)(5)(B) requires "Each group health plan shall establish reasonable procedures to determine whether medical child support orders are qualified medical child support orders and to administer the provision of benefits under such qualified orders." Nothing more definite than that regarding your issue.

I don't know that the 31 day requirement would qualify as reasonable. You might want to get a legal opinion before trying to impose that 31 day requirement. Generally, it would be better from a claims and cost management and business operations perspectives to know who you are covering and collect the premium from the employee than to have a court second guess you and order coverage you had denied.

What does 31 days have to do with whether or not a MCSO qualifies? There is nothing date sensitive about the timing of the orders, so how can the plan impose some time requirement? The plan can choose give effect to the order prospectively, so delay between the date the order is issued and the date of receipt by the plan can affect the timing of coverage, but not the application of the order.

No. QMCSOs are written to generically apply to any employer/plan administrator so as to be used should the employee change jobs and without having to return to court to reword the order for a specific employer/plan administrator. Therefore, QMCSOs can potentially be given to current and future employers/plan administrators well beyond 31 days of the order's issue date.

A plan administrator cannot deny a QMCSO because the order is more than 31 days old when an ordered parent changes jobs 5 years after the order was issued and submits a 5 year old order to the new plan administrator.

It is also not allowed to set a limit to require submission of the QMCSO within 31 days of the parent becoming eligible, say in the case of a new hire, or even within 31 days of open enrollment for current employees.