Hi,

In V13 also you can define allowances and deductions.

You will be able to create salary rules and salary structures the same as in old versions. 
Payroll -> Configuration -> Rules(Salary Rule) 

Payroll -> Configuration -> Structures(Salary Structure)

​In addition to this there is a new field which is created in the Employee contract called 'Salary Structure Type' instead of Salary structure. And we can define different salary structures inside a Salary Structure Type. Now while creating the contract you need to choose the salary structure type and when comes to create the payslip you need to choose the employee first. And when the employee is chosen then automatically the following fields will appear. Then there you will be able to see the field called Structure(Salary structure). Here you will be able to choose a different salary structure which you already defined earlier.

Hope this helps.