1591 Background: A breast cancer (BC) diagnosis places physical, emotional, and financial stress on patients. The full spectrum of administrative burdens that patients carry, while simultaneously dealing with cancer treatment, is unexplored. Methods: From 6-7/2022, Breastcancer.org community members consented to an anonymous online survey in English or Spanish. The survey assessed patient-reported disability claims [short-term (ST) or long-term (LT)], FMLA application, and appeals of insurance claim denials. Multivariable analysis (MVA) modeled associations with 1) disability application and 2) helpfulness of FMLA. Eligibility included: US resident, age ≥ 18, and BC diagnosis within 10 years. Results: Of 2,420 members screened, 1,710 met eligibility, and 1,437 completed the survey (84% participation rate). Nearly all (94%) identified as women; 60% identified as White, 27% Hispanic, 8% Black, or 4% Other race. Median age was 46 years (range: 19-85), and median time since diagnosis was 2 years (range: 0-10). 75% were on active treatment; 11% had metastatic disease. About one-third of respondents (32%) applied for ST disability, and 26% for LT disability (10% applied for both). A lower proportion of White patients applied for disability (ST: 17% White, 25% Black, 33% Hispanic; LT: 9%, 15%, 35%, both p<0.001). Patients with metastatic disease applied for LT disability more often (23% vs 16% non-metastatic, p=0.01). Although most were approved (74% ST, 63% LT); about one-quarter (23% ST, 29% LT) found disability very/extremely difficult to apply for, with no variation by race, ethnicity, or disease status (all p>.05). On MVA, Hispanic patients (OR=5.39, 95%CI 3.96-7.34) and those with metastatic disease (OR=1.52, 95%CI 1.01-2.30) had increased odds of filing for disability. Of respondents who filed for FMLA (27%), 25% found it a very/extremely difficult application. Of 289 FMLA recipients, one-half found it very/extremely helpful. On MVA, longer time since diagnosis was associated with perceived helpfulness (OR=1.16, 95%CI 1.03-1.30). One-third of respondents filed an appeal of an insurance denial: this was more common among those with metastatic disease (41% vs 32% non-metastatic, p=0.02) and less common in White patients (26% White, 39% Black, 45% Hispanic; p<0.001). Of respondents who appealed, most (57%) filed between 2-5 times; patients with metastatic disease were more likely to have to file >5 times (18% vs 7%, p=0.005). Conclusions: Patient administrative burden impacted one-third of BC patients, with larger burdens on historically marginalized or minoritized groups (e.g., Black and Hispanic patients; those with metastatic disease). State and national legislative priorities should work to standardize and streamline application processes so patients can have the financial stability to focus on cancer treatment and recovery goals.