Going the extra mile? General practitioners' upcoding of fees for home visits

General practitioners' (GPs') income often relies on self-reported activities and performances. They can therefore 'game the system' to maximize their remuneration. We investigate whether Danish GPs game their travel fees for home visits. Combining administrative and geographical data, we measure the difference between GPs' traveled and billed distances. We exploit a rise in the fees for home visits. If there is a link between the rise in fees and upcoding, we interpret this finding as indicative of gaming behavior. We find that upcoding occurs slightly more often than downcoding (16% vs. 13% of visits) for visits that can be both upcoded and downcoded. Using linear probability models with GP fixed effects, we find that the fee rise is associated with a reduction in upcoding of 0.6% of home visits (2.8% for visits where upcoding is feasible) and no change in downcoding. Importantly, we find no statistically significant differences in the reduction in upcoding across distance bands despite large differences in their fee rises. We therefore conclude that there is no causal evidence of GPs gaming their fees.