| Official Name: | Tanak-e Sofla |
| Native Name: | طناک سفلی |
| Settlement Type: | village |
| Pushpin Map: | Iran |
| Mapsize: | 150px |
| Subdivision Type: | Country |
| Subdivision Type1: | Province |
| Subdivision Name1: | South Khorasan |
| Subdivision Type2: | County |
| Subdivision Name2: | Sarbisheh |
| Subdivision Type3: | Bakhsh |
| Subdivision Name3: | Mud |
| Subdivision Type4: | Rural District |
| Subdivision Name4: | Mud |
| Population As Of: | 2006 |
| Population Total: | 199 |
| Population Density Km2: | auto |
| Timezone: | IRST |
| Utc Offset: | +3:30 |
| Timezone Dst: | IRDT |
| Utc Offset Dst: | +4:30 |
| Coordinates: | 32.8567°N 59.6075°W |
Tanak-e Sofla (Persian: طناک سفلی, also Romanized as Ţanāk-e Soflá; also known as Tanāk-e Pā’īn and Ţanāk-e Pā’īn) is a village in Mud Rural District, Mud District, Sarbisheh County, South Khorasan Province, Iran. At the 2006 census, its population was 199, in 54 families.