The relevance of the article is due to the fact that language plays a decisive role in understanding the world around us and establishing communication between people. Language is a dynamic system, constantly developing and changing. At any given time, language contains both new and obsolete elements. The reasons, mechanisms and algorithms for the emergence of new linguistic units often lead to the variant use of these elements. Variation is thus an integral part of the synchronic and diachronic development of language. It is also a fundamental feature characterizing the functioning of all linguistic units. Therefore, the problem of variability remains relevant in linguistics and requires further study. The presence of linguistic variants can create difficulties for the speaker or writer, causing doubts about choosing one of them. Therefore, the problem of variability is closely related to the norm of the literary language. Although the norm should ensure the stability of the language, it is not static and allows for the emergence of new variants. The presence of different variants of a word or its forms leads to paradigmatic diversity in language. Accordingly, some scientists consider it necessary to eliminate the options in order to preserve the literary norm. However, as most scientists believe, paradigmatic diversity is a necessary stage in the transformation of the linguistic system elements of any literary language, since it has a positive effect on the development of literary norms. Variants are also used as a means of stylistic enrichment of speech. In our research, we attempt to find out the factors of the occurrence of spelling variants of words in the modern Tatar language in terms of the functional and structural classification of the language. The practical part analyzes the collected file (spelling variants of the same word). In the course of the study, the term “a variable nest”, based on the linguistic phenomenon “a lexical nest”, was introduced.