Calculation regarding lump sun withdrawal benefit?

How does the calculation work regarding lump sum withdrawal benefit (3920) from Sanlam Life Insurance Ltd and is the any deduction on that amount?

Please make use of our Lump sum calculator to work out the tax due on your lumpsum. Your employee will need to apply for a tax directive when you withdraw and the net amount will be paid to you (and the tax due paid to SARS).