Economic evaluations require patient-level resource-use to estimate patient costs. The National Programme for IT (2002) prompted UK health and social care to record patient-level resource-use using Electronic Administration Records (EAR’s). Retrieving EAR’s is labour intensive, but may provide better information than self-report methods, such as the Client Service Receipt Inventory (CSRI), particularly in cognitively impaired people. Study objectives are to examine agreement, and associated cost estimates, between resource-use obtained from EAR’s or CSRI in frail older (≥70) participants. METHODS: Health and social care data for 247 patients (193 cognitively impaired) were sought retrospectively six months post-index hospital admission. Resource-use data were collected using a self/proxy-reported modified CSRI, and EAR systems for primary (PC), secondary (SC), and social (SoC) care. Lin’s coefficient (ρc) assessed agreement between methods, where <0.4 = poor agreement. RESULTS: Agreement between EAR and CSRI ‘per contact’ resource-use was: good, primary care (ρc = 0.60); fair, outpatient care (ρc = 0.53). Agreement was incomparable for social care due to different resource-use recording formats; CSRI’s inpatient care question was removed due to the preferred detailed information available in EAR’s. EAR data provided detailed patient care information, such as diagnosis and procedure type, allowing improved allocation of unit costs. Difference in mean cost per patient between methods varied by service (CSRI/EAR (£): PC = 61/433; SC = 7281/7833; SoC = 252/886); CSRI inpatient costs were simulated assuming perfect agreement with EAR, but using level of information outlined within the CSRI. CONCLUSIONS: EAR’s provided more complete patient costs. Using EAR’s reduces burden upon participants, which is important for frail and cognitively impaired people. Although the CSRI can be modified and simple to administer, poor recall and inadequate detail about patient care contacts prevented accurate patient-level cost estimation. Gaining access to EAR’s is labour intensive, but recommended in cognitively impaired participants.