There are many different kind of agreements, conditions and rules that are governed by the internal legislation in the jurisdiction where the parent company is established.
Regardless of what your agreement says about favourable tax treatment, Swedish tax law rules if you live and work in Sweden.
Your employer gives you an offer to participate in a stock purchase plan. This plan gives you the right to buy shares in the future on favourable conditions. The employer is allowed to withhold a part of your salary which will be deposited on your account. Normally, the administration is kept externally. At the end of the period (normally six months) as many shares as possible are bought with the saved amount.
The benefit arises the day when the shares are bought and the value is the difference between the fair market value and the price you have paid.
When you decide to sell your shares you report this as capital gain. The taxed value of the benefit is added to the cost of acquisition when the capital gain is computed.