                 +----------------------+
                 |  ContractSettngs     |  <<abstract dataclass>>
                 +----------------------+
                 | - name: str | None   |
                 | - current_month_gross_sum: Decimal |
                 | - social_security_base_sum: Decimal |
                 | - cost_fifty_sum: Decimal |
                 | - tax_base_sum: Decimal |
                 | - employee_ppk: Decimal |
                 | - employer_ppk: Decimal |
                 | - accident_insurance_rate: Decimal | None |
                 | - salary_deductions: Decimal |
                 +----------------------+
                 | +to_exporter_dict()  |
                 | +to_dict() <<abstract>> |
                 | +options_type()      |
                 +----------------------+
                          ^
                          |
        -------------------------------------------------
        |                 |               |           |
+----------------+  +----------------+  +----------------+  +----------------+
| Employment     |  | Mandate        |  | SelfEmployment |  | WorkContract  |
| ContractSettings|  | ContractSettings|  | Settings       |  | Settings      |
+----------------+  +----------------+  +----------------+  +----------------+
| - increased_costs: bool                ...               ... etc
| - cost_fifty_ratio                     ...               ...
| - fp_fgsp
| - active_business
| - under_26
| - sick_pay
+----------------+ ... etc

