The declension of surnames in the Russian language has its own characteristics, depending primarily on the origin of the words. Even philologists sometimes find it difficult to do this, especially if the proper name has two options, and in each of them it sounds correctly.
The characteristic ending for Russian surnames will be -sky (s), -s (-s), -in (-s). This also includes proper names formed without a suffix (for example, Tolstoy). The declension of surnames of this origin will be similar to the change of adjective names. For example, “Petrov Ivan”, “Petrova Anna”. As you can see, in this case, the names change depending on the gender (male or female, respectively).
Another rule applies to those proper names that have a foreign origin and end in -i or are formed from frozen forms (Smooth, Gray-haired). Such names are not inclined. Surnames such as Zhivago, Semenyago, and others ending in -ago, -iago also do not change.
Declination of male surnames in some cases differs from female. So, if at the end of the last is a consonant, then they will not change. For example, you can say: “Let Lilia German speak!” But: “Pass the salt to Vladimir German.” Thus, the same surnames, formed in an unconventional way or borrowed from other languages, ending in a consonant, change in cases as nouns, if they refer to men, and are pronounced in their original form, if they belong to women.
The exception is the declension of Armenian surnames. In this case, regardless of which gender the address is addressed, it remains unchanged. For example, "Karen Martirosyan" or "Diana Martirosyan."
Many Russian surnames end with -co. Mostly they came from the Ukrainian language (Shevchenko, Tarasenko, etc.). These words also do not change, regardless of who they turn to: a woman or a man. It is especially important to take into account such nuances in official documents.
Declination of surnames having a foreign origin and ending in a vowel sound (Dumas, Hugo, Zola) often causes difficulties. It must be remembered that in this case, the words do not change with any treatment. At the same time, Russian borrowed surnames that have an unstressed sound (s) in the end (Okudzhava, Varava, Kafka) are inclined according to the principle of nouns. An exception here will be only those in which the penultimate is the vowel -and. For example, Garcia, Moriah.
The declension of surnames at the end of which there is a percussion -a (Skovoroda) is possible only if they are of Slavic origin. Borrowed words remain unchanged (for example, Dumas books). Male surnames, at the end of which are -e, -e, -y, -y (Ordzhonikidze, Korodzhali, etc.) are not inclined.
In compound names of Korean or Vietnamese origin, only the last part is inclined. In Russian double surnames , both parts change if each of them is used in a different form (for example, Lebedev-Kumach). Otherwise, the first word must be left in its original form (Skvoznik-Dmukhanovsky).
The rules by which names are declined are very important when processing various documents or simply when contacting a friend so as not to get into an awkward situation.