Being tax compliant generates costs and these costs affect small business tax compliance behaviour and contribution. This study uses multiple regression analyses to investigate the key drivers of small business’s internal tax compliance costs (hours spent internally on tax compliance activities). This will assist Revenue Services in understanding what factors (determinants) could increase a small business’s internal tax compliance costs and might assist in managing tax compliance behaviour and contribution. The results expose the significant determinants per tax type, enabling a comparison to be made across the different tax types. Overall, turnover is the variable that had the most significant influence on internal tax compliance costs (time) (as opposed to the number of employees, which had a significant effect only on the internal time spent on employees’ tax). The analysis confirmed that there is a higher proportional burden for smaller businesses in respect of internal income tax and employees’ compliance activities.