Abstract Background Thirty-day readmissions are common in general surgery patients and affect long-term outcomes including mortality. We sought to determine the effect of complication timing on postoperative readmissions. Methods Patients from our institutional American College of Surgeons National Surgical Quality Improvement Project database who underwent general surgery procedures from 2006 to 2011 were included. The primary outcome of interest was 30-day hospital readmission. Results Patients diagnosed with postdischarge complications were significantly more likely to be readmitted (56%) compared with patients diagnosed with complications before discharge (7%, P < .001). Independent predictors of postdischarge complications included laparoscopic case, short hospital stay, preoperative dyspnea, and independent functional status. Gastrointestinal complications and surgical site infection were the most common reasons for readmission. Conclusions The development of complications after hospital discharge places patients at significant risk for readmission. Early identification and treatment of gastrointestinal complications and surgical site infections in the outpatient setting may decrease postoperative readmission rates.