Research shows that undocumented migrants have difficulties in accessing healthcare. Act 2013:407 came into force in 2013 and entitled undocumented migrants to healthcare that cannot be deferred. To date, studies about undocumented migrants' access to care in Sweden and the impact of Act 2013:407 are sparse. Hence, the aim of this study was to describe professionals' experiences of access to healthcare for undocumented migrants in Sweden and the impact of Act 2013:407. A qualitative design with semi-structured interviews was employed. Nine interviews were carried out in 2015 with nurses at two NGO healthcare centres for undocumented migrants - and an additional seven interviews in 2022 with staff at an NGO healthcare centre for undocumented migrants and personnel at a regional health and medical care administration. Interpretive description was used for the analyses. Permission to carry out the study was obtained from managers at the participating NGOs and the regional health and medical care administration. Participants received verbal and written information about the study, and informed consent was obtained from all participants. Six categories emerged from the analysis: Changes since the Act was introduced, General problems with healthcare access, Care for undocumented migrants - politics and social economy, Lack of knowledge, 'Healthcare that cannot be deferred' and Being an undocumented migrant. Undocumented migrants' social needs are as great as their needs for healthcare. Healthcare staff are burdened with healthcare cost considerations which affect their judgement of care provision and prioritization. Healthcare staff attitudes towards undocumented migrants affect their access to healthcare. Undocumented migrants in need of healthcare are especially vulnerable due to their legal status, being ill and the fear of being reported and deported. To assure undocumented migrants' access to healthcare and maintain healthcare ethics, the only possible solution is to provide healthcare based on needs.