BECCS (here the combination of forest-based bioenergy with carbon capture and storage) is seen as a promising tool to deliver the large quantities of negative emissions needed to comply with ambitious climate stabilization targets. However, a land-based mitigation option such as large-scale bioenergy production (without CCS) might interfere with other land-based mitigation options popular for their large co-benefits such as reduced emissions from deforestation and degradation (REDD+). We develop a systems approach to identify and quantify possible trade-offs between REDD+ and BECCS with the help of remote sensing and engineering modeling and apply this for illustration to Indonesia. First results indicate that prioritizing REDD+ does imply that there the BECCS potential remains limited. Further research is needed to take into account opportunities where the two options could be deployed synergistically, capitalizing on co-benefits. BECCS and REDD+ must be evaluated from a portfolio perspective, as estimating their potentials independently will not take such opportunities into account.