Income maximisation may reduce enduring poverty-related health inequalities. Specialist welfare rights advice in primary care has been proposed and, in some areas, implemented, but evaluation data from the general practice perspective is needed. The present study aimed to evaluate the impact on general practice of specialist welfare rights advice, comparing practices with and without in-house provision of welfare advice using a cross-sectional postal questionnaire. This study was conducted in general practice surgeries in an inner-London health authority with high indicators of deprivation. Questionnaires were sent to practice managers. Comparative data (according to whether specialist advice was currently offered) addressed processes of identifying and meeting welfare needs and outcomes in terms of efficiency of provision. Seventy-nine surgeries participated. Those with welfare rights advisers (n = 42) were significantly more likely to report that current provision was adequate, that it was easier for staff to access advice on their patients' behalf (and by patients themselves) and that the process of advice provision ran smoothly. Lack of funding and space were the principal reasons for not having in-house advice. Surgeries wish provision to be expanded within practices. Welfare rights advice in surgeries improves ability to meet welfare needs via specialist advisers. Referral processes are simplified, enabling general practitioners to ensure that relevant advice is provided without the need for welfare knowledge themselves. General practices welcome the expansion of provision, with the proviso that adequate resources are identified. The current lack of basic information in surgeries must be addressed (e.g. information on local providers, printed information detailing range and eligibility criteria of welfare benefits).