Year-end bonuses are not regulated by law. This means that individual enterprises decide for themselves whether to grant year-end bonuses and if so, how much to pay.

The SAP standard system contains the following variants for the payment of year-end bonuses:

• Variant 1: Payment of year-end bonus on the basis of average factored (reduced) monthly wage
  The monthly wage is cumulated for all periods up to the payment period. This cumulated wage forms the basis of the payment of the 13^th monthly wage.
  The employee receives a portion of 1/12 of the basis of the 13^th monthly wage. In the payment month, the cumulation basis is reset and reserves are paid out.
  This variant takes employees who enter or leave the enterprise during a period into account.
  
  The 13^th monthly wage is to be paid in two installments, one in June and one in November. The employee enters the enterprise on April 16. From April to September, he or she receives a monthly wage of 6,000 SFr. From October to December, he or she receives a monthly wage of 10,000 SFr.
  In June, he or she receives an installment for the 13^th monthly wage in the amount of 1,250 SFr
  (3,000 + 6,000 + 6,000) / 12 = (15,000 / 12) = 1,250 SFr).
  In November, there is a second installment in the amount of 4,000 SFr
  (6,000 + 6,000 + 6,000 + 10,000 + 10,000 +10,000) / 12 = (48,000 / 12) = 4,000 SFr).

• Variant 2: Payment on the basis of current, non-factored monthly wage
  The current, non-factored wage of the payment period is used as a basis for the payment. This wage is credited to the employee for the entire year, provided that he or she is active in the payment period and irrespective of when he or she entered the enterprise and whether he or she has unpaid absences.
  
  The 13^th monthly wage is to be paid in two installments, one in June and one in November. The employee enters the enterprise in May. From May to September, the employee receives a wage of 6,000 SFr. From October to December, the employee receives a wage of 10,000 SFr.
  In June, the employee receives a year-end bonus installment in the amount of 3,000 SFr
  (6,000 / 2 installments = 3,000 SFr).
  In November, a second installment in the amount of 5,000 SFr is paid
  (10,000 / 2 installments = 5,000 SFr).

• Variant 3: Payment on the basis of current monthly wage projected to the entire period under consideration
  Unlike variant 1 (average wage), this variant does not cumulate the wage for all the periods under consideration. Instead, it cumulates the partial period factors of individual periods. In the payment period, the current period wage is projected to the period under consideration using the cumulated partial period factors. 1/12 of the basis formed in this way is paid as an installment of the 13^th wage. In this way, entries/leavings and unpaid absences are taken into account.

• Variant 4: Payment on the basis of average non-factored monthly wage
  If the calculation is performed using this method, the monthly wage is cumulated for all periods up to the payment period. If an employee enters or leaves the enterprise during a period, a complete (that is, non-factored) monthly wage is used for the calculation.
  
  The 13^th monthly wage is to be paid in two installments, one in June and one in November. The employee enters the enterprise in mid-April. From April to September, the employee receives a wage of 6,000 SFr. From October to December, he or she receives a wage of 10,000 SFr.
  In June, the employee receives an installment in the amount of 1,500 SFr
  (6,000 + 6,000 + 6,000) / 12 = (18,000 / 12) = 1,500).
  In November, a second installment in the amount of 4,000 SFr is paid to the employee
  (6,000 + 6,000 + 6,000 + 10,000 + 10,000 +10,000) / 12 = (48,000 / 12) = 4,000).

Paying out reserves
Reserves are formed and paid out using the same procedure for all calculation variants. In each month, 1/12 of the factored period salary is stored as a reserve. In the payment periods, the reserve is paid out.
If the last payment period is before December, the reserve is paid out for a period after the current period, which means a negative reserve is created. At the end of the year, the total reserve amount is zero because a reserve of 1/12 of the period wage is created again in the following months.

Proportional payment for employee who leaves/retires
Variants 1, 3, and 4 enable you to effect a proportional payment for an employee who leaves the enterprise or retires. However, this is not possible for variant 2.

 You define the formation of bases for year-end bonuses in Customizing for Payroll: Switzerland by choosing Year-End Bonuses -> Calculation of Year-End Bonuses as of Release 4.0 -> Determine Calculation Formulas for Year-End Bonuses.