Telecommute Tax Relief Gathers Steam
You may be misreading your weekly pay stub.
The state tax refund is treated as "additional" income because it wasn't taxed to begin with. It's withheld from your net paycheck and, therefore, not taxed as income at that time. When you get it back via refund, it goes back in the "taxable income" column and is then taxed - after the fact.
The feds do the same thing, in case you haven't noticed. You're supposed to declare any state tax refunds on your federal return.
In all cases, the one-year-free-loan is accurate, though. And you can adjust your W-4 to deal with that (declare more 'dependents'). Instead of overpaying, just resign yourself to paying at the end of the year, but in which case you get to keep more of your earnings.