In today’s internet age, when many people can use the web to run the child support guidelines, counsel may seem obsolete. Let me assure you—in Massachusetts, when SSDI dependency benefits are involved, it gets tricky. Under Rosenberg v. Merida, if a payor parent receives SSDI and the children receive the derivative dependency benefits, the dependency benefit must be added to the payor parent’s income for child support worksheet purposes. Then look at the figure the child support worksheet calculates. If the dependency benefit is greater than the child support calculation, the payor parent does not need to pay any additional child support. If the dependency benefit is less than the child support calculation, subtract the dependency benefit from the child support calculation. The remainder is the amount the payor parent must pay for child support each week.