This is a liability since technically if the employee were to terminate you would owe them the money back. Deposit the money using a payroll liability account. When you next bill comes, enter the amount of the bill however in the expense portion, enter the total less the employees monthly premium. Drop down a line and use the payroll liability account in the amount of that month's premium. You might want to set up a separate liability account so that you can easily track the declining balance down to zero.
