Primary care providers prescribe most long-term opioid therapy and are increasingly asked to taper the opioid doses of these patients to safer levels. A recent systematic review suggests that multiple interventions may facilitate opioid taper, but many of these are not feasible within the usual primary care practice.To determine if opioid taper plans documented by primary care providers in the electronic health record are associated with significant and sustained opioid dose reductions among patients on long-term opioid therapy.A nested case-control design was used to compare cases (patients with a sustained opioid taper defined as average daily opioid dose of ≤ 30 mg morphine equivalent (MME) or a 50% reduction in MME) to controls (patients matched to cases on year and quarter of cohort entry, sex, and age group, who had not achieved a sustained taper). Each case was matched with four controls.Two thousand four hundred nine patients receiving a ≥ 60-day supply of opioids with an average daily dose of ≥ 50 MME during 2011-2015.Opioid taper plans documented in prescription instructions or clinical notes within the electronic health record identified through natural language processing; opioid dosing, patient characteristics, and taper plan components also abstracted from the electronic health record.Primary care taper plans were associated with an increased likelihood of sustained opioid taper after adjusting for all patient covariates and near peak dose (OR = 3.63 [95% CI 2.96-4.46], p < 0.0001). Both taper plans in prescription instructions (OR = 4.03 [95% CI 3.19-5.09], p < 0.0001) and in clinical notes (OR = 2.82 [95% CI 2.00-3.99], p < 0.0001) were associated with sustained taper.These results suggest that planning for opioid taper during primary care visits may facilitate significant and sustained opioid dose reduction.