Tanja is a locality in the Bega Valley Shire of New South Wales, Australia. At the 2016 census, Tanja had a population of 157.

Tanja Public School is situated on Barrabooka Road. The school had an enrolment of 17 in 2017. It dates from 1878, having originally begun in a room of the school teacher's own residence.

Tanja Post Office opened on 1 September 1878 and closed on 28 August 1980.

Heritage listings

Tanja has a number of heritage-listed sites, including:

• Haighs Road (within Mimosa Rocks National Park): Penders
• Nelson Lake Road, Nelson Lagoon, Mimosa Rocks National Park: Baronda