Bassignac-le-Bas is located some 30 km south-east of Brive-la-Gaillarde and 10 km south-west of Argentat. Access to the commune is by the D116 which comes from Argentat in the north-east and passes along the riverbank through the commune before continuing south to join the D940 at Beaulieu-sur-Dordogne. The D41 from Beaulieu-sur-Dordogne to La Chapelle-Saint-Géraud passes through the south-west of the commune. The D136 comes from Brivezac across the river and passes through the commune eastwards to join the D41 in the east of the commune. Apart from the village there are the hamlets of Vaurs, Recoudier, Le Peuch, Culagne, Chaviolle, La Gendrie, Le Gasquet, Brette, and La Laurie in the commune. The commune is mixed forest and farmland.
The Dordogne river forms the western and northern borders of the commune as it flows south to eventually join the Garonne at Bayon-sur-Gironde. The Ruisseau de la Borie flows from a small lake in the east of the commune westwards to join the Dordogne. The Ruisseau de Layssot forms the north-eastern border of the commune as it flows north to join the Dordogne. The Ruisseau de Chauvac forms the southern border of the commune as it flows west to join the Dordogne.
In 2010 the commune had 90 inhabitants. The evolution of the number of inhabitants is known from the population censuses conducted in the commune since 1793. From the 21st century, a census of communes with fewer than 10,000 inhabitants is held every five years, unlike larger communes that have a sample survey every year.[Note 1]
^At the beginning of the 21st century, the methods of identification have been modified by Law No. 2002-276 of 27 February 2002, the so-called "law of local democracy" and in particular Title V "census operations" allows, after a transitional period running from 2004 to 2008, the annual publication of the legal population of the different French administrative districts. For communes with a population greater than 10,000 inhabitants, a sample survey is conducted annually and the entire territory of these communes is taken into account at the end of the period of five years. The first "legal population" after 1999 under this new law came into force on 1 January 2009 and was based on the census of 2006.