International Journal of Neutrosophic Science IJNS 2690-6805 2692-6148 10.54216/IJNS https://www.americaspg.com/journals/show/4082 2020 2020 Department of Mathematics, School of Science, University of Phayao, 19 Moo 2, Mae Ka, Mueang, Phayao 56000, Thailand Aiyared Aiyared Department of Mathematics, Sri Eshwar College of Engineering, Coimbatore-641202, Tamil Nadu, India Vennila Ramasamy Department of Mathematics, Sri Sarada College for Women (Autonomous), Salem-636016, Tamil Nadu, India V. Vijaya Bharathi Department of Mathematics, Rajah Serfoji Government College (affiliated to Bharathidasan University), Thanjavur-613005, Tamil Nadu, India K. Geetha Department of Mathematics, Rajah Serfoji Government College (affiliated to Bharathidasan University), Thanjavur-613005, Tamil Nadu, India Neelamegarajan Rajesh In this paper, we conduct a comprehensive study of neutrosophic subalgebras of various types within the framework of Sheffer stroke UP-algebras (SUP-algebras). Specifically, we introduce and characterize (∈, ∈), (∈, ∈ ∨q), and (q, ∈ ∨q)-neutrosophic subalgebras based on neutrosophic ∈-subsets, q-subsets, and (∈ ∨q)-subsets. Necessary and sufficient conditions are established for these subsets to form subalgebras under the Sheffer stroke operation. Several theorems demonstrate how these types interrelate and differ in their structural properties, with illustrative examples provided. Furthermore, we identify the conditions under which certain canonical subsets, such as X1 0 = {x ∈ X | T (x) > 0, I(x) > 0, F (x) < 1}, form subalgebras across differ- ent neutrosophic configurations. These results offer a unified perspective and deeper insight into the algebraic behavior of neutrosophic systems in the context of SUP-algebras. 2026 2026 351 359 10.54216/IJNS.270229 https://www.americaspg.com/articleinfo/21/show/4082