The UK government is promoting the health benefits of work, in order to change doctors’ and patients’ behaviour and reduce sickness absence. The rationale is that many people ‘off sick’ would have better outcomes by staying at work; but reducing the costs of health care and benefits is also an imperative. Replacement of the ‘sick note’ with the ‘fit note’ and a national educational programme are intended to reduce sickness-certification rates, but how will these initiatives impact on doctor–patient relationships and the existing tension between the doctor as patient advocate and gate-keeper to services and benefits? This tension is particularly acute for problems like chronic pain where diagnosis, prognosis and work capacity can be unclear. We interviewed 13 doctors and 30 chronic pain patients about their experiences of negotiating medical certification for work absence and their views of the new policies. Our findings highlight the limitations of naïve rationalist approaches to judgements of work absence and fitness for work for people with chronic pain. Moral, socio-cultural and practical factors are invoked by doctors and patients to contest decisions, and although both groups support the fit note’s focus on capacity, they doubt it will overcome tensions in the consultation. Doctors value tacit skills of persuasion and negotiation that can change how patients conceptualise their illness and respond to it. Policy-makers increasingly recognise the role of this tacit knowledge and we conclude that sick-listing can be improved by further developing these skills and acknowledging the structural context within which protagonists negotiate sick-listing.