What about your tax code, the amount of money you dont pay tax on each year, surely some of that ammount can be sorta added to your weeks gross salary, as you shouldnt be being taxed on that bit of your earnings.
Know my tax code just changed a bit and altered my monthly net figure by a bit.
Have personaly always just deducted a third from gross earnings to get the net, never normally to the penny lol, but gives a good idea of what to expect, and if the wages dept have made a big fook up
Steve