The attractive sounding salary that you are being offered on the table is your 'gross' salary, the wage that actually goes into your bank account is your 'net' salary. Somewhere in the middle the taxman takes his cut, and you pay National Insurance contribution.
To compensate for tax loss and in a bid to woo high fliers away from the competition employers may offer further sweeteners on top of your basic salary. These incentives can come in many forms for example, health schemes, a company car, or share options. There can be hidden costs with each of these, and their value may alter with stock market and interest rate fluctuations. Serious consideration needs to be made when accepting anything on top of, or as a part of your salary because once you sign on the dotted line there is no going back.