Background The Society of Surgical Oncology and American Society of Radiation Oncology consensus statement was the first professional guideline in breast oncology to declare “no ink on tumor” as a negative margin in patients with stages I/II breast cancer undergoing breast-conservation therapy. We sought to analyze the financial impact of this guideline at our institution using a historic cohort. Study Design We identified women undergoing re-excision after breast-conserving surgery for invasive breast cancer from 2010 through 2013 using a prospectively maintained institutional database. Clinical and billing data were extracted from the medical record and from administrative resources using CPT codes. Descriptive statistics were used in data analysis. Results Of 254 women in the study population, 238 (93.7%) had stage I/II disease and 182 (71.7%) had invasive disease with ductal carcinoma in situ. A subcohort of 83 patients (32.7%) who underwent breast-conservation therapy for stage I/II disease without neoadjuvant chemotherapy had negative margins after the index procedure, per the Society of Surgical Oncology and American Society of Radiation Oncology guideline. The majority had invasive ductal carcinoma (n = 70 [84.3%]) and had invasive disease (n = 45 [54.2%]), and/or ductal carcinoma in situ (n = 49 [59.0%]) within 1 mm of the specimen margin. Seventy-nine patients underwent 1 re-excision and 4 patients underwent 2 re-excisions, accounting for 81 hours of operative time. Considering facility fees and primary surgeon billing alone, the overall estimated cost reduction would have been $195,919, or $2,360 per affected patient, under the guideline recommendations. Conclusions Implementation of the Society of Surgical Oncology and American Society of Radiation Oncology consensus guideline holds great potential to optimize resource use. Application of the guideline to a retrospective cohort at our institution would have decreased the overall re-excision rate by 5.6% and reduced costs by nearly $200,000. Additional analysis of patient outcomes and margin assessment methods is needed to define the long-term impact on surgical practice.