The conceptual framework is based on the works of Grant23 27 28 30
| Factor | Operationalisation |
| Purpose | What is the purpose of the fee and is it acceptable to the parties involved? |
| Voluntariness | Does the fee allow for an informed and voluntary response? |
| Character | Does the fee affect the individual character or institutional culture, including effects on altruism, responsibility or the intrinsic motivation to act? |
| Fairness | Is the fee administrated fairly so that people who are similarly situated are treated alike? |
| Effectiveness | Is the fee an effective means of achieving the goal compared with the alternatives? |
| Undue influence | Is the fee issued by decision-makers with legitimate authority in the sphere in which the fee is issued? Does the fee induce people to act against their better judgement or principles? |