This paper introduces the concept of Non Trivial Online Forms (N-TOFs). We characterise these forms in terms of their criticality to the life and well-being of individuals such as where they are the primary route to legal, financial, employment related, medical or other important transactions. The aim of the research is to develop a usability analysis model which will evaluate the N-TOF by engaging the form designer in reflecting upon characteristics of the form. From this an assessment of form usability quality will be measured against the ISO standard 9241: 210 on Human-centred design for interactive systems. Where possible this model based output would be formative helping the designer address areas needing improvement within an N-TOF as a whole or a section of an N-TOF.