Abstract
The paper is mixed-method research on reducing administrative burden and, more specifically, the learning costs of filling out a property tax declaration form. It presents the development process of a guidebook, which simplified the instructions and experimentally tested the effectiveness of the guidebook in lowering the error rate. Young Slovak adults (N=43) were divided into two groups; the treatment group worked with the guidebook, and the control group used the official instructions the Ministry of Finance provided. The guidebook aimed to decrease learning costs using behavioural support (simplification, highlighting, examples, and the like). The results suggest that the guidebook helps significantly decrease the number of errors compared to the complex instructions the Ministry of Finance provided. However, while the guidebook is very effective in reducing errors in simple tasks, it may not be sufficient help for more complex tasks such as mathematical calculations. Therefore, simplified instructions must go hand-in-hand with interventions such as pre-populating of forms.