This policy brief reflects on an underexplored proposition: that bilateral tax treaties – particularly treaties involving (middle- and) low-income countries – should contain an expiration or sunset clause. The brief examines some reasons why it may be sensible for a low-income country to make its bilateral tax treaty expirable, from its onset. It also highlights a few reasons why such a policy may not be advisable – or tenable. The brief concludes by exploring the design of a model sunset clause for inclusion in the UN Model Tax Convention.