Few studies have assessed the impact of co-morbid conditions amongst patients with arthritis. This study will quantify the impact co-morbid health conditions have on the labour force status and economic circumstances of people with arthritis. This study uses a microsimulation model, HealthWealthMOD, to quantify the impact of co-morbidities on the labour force participation and economic circumstances of 45- to 64-year-old Australians with arthritis. The results show that the probability of being out of the labour force increases with increasing number of co-morbidities. However, there was no statistically significant difference in the amount of weekly private income received by people with arthritis and no co-morbidities, and people with arthritis and one or two co-morbidities. However, those with arthritis and three or more co-morbidities received a weekly private income 72 % lower than people with arthritis alone (95 % CI -82, -57). People with arthritis and co-morbidities paid less in tax and received more in government transfer payments. As such, it is important to consider the co-morbid conditions an individual has when assessing the impact of arthritis on labour force participation and economic circumstances. People with arthritis that have multiple co-morbid conditions are likely to have their labour force participation and economic circumstances interrupted much more than those with arthritis only.