diff --git a/models/answer.py b/models/answer.py
index e66bc16..fc7dd0e 100644
--- a/models/answer.py
+++ b/models/answer.py
@@ -5,6 +5,7 @@ from typing import TypeAlias, Annotated
 from pydantic import field_validator, field_serializer, Field
 
 from models import BaseModel, form
+from utils import validate_tin, validate_snils
 
 
 class AnswerError(Enum):
@@ -13,7 +14,10 @@ class AnswerError(Enum):
     TOO_FEW_SELECTED = "The number of selected items is less than the minimum required."
     TOO_MANY_SELECTED = "The number of selected items is more than the maximum allowed."
     DUPLICATE_QUESTIONS = "Each value must correspond to a different question."
+    REQUIRED_QUIESTION_NOT_ANSWERED = "The required question was not answered."
     INCORRECT_IDS = "The ids for some questions are incorrect."
+    TIN_VALIDATION_FAILED = "The TIN validation process failed."
+    SNILS_VALIDATION_FAILED = "The SNILS validation process failed."
 
 
 class BaseValue(BaseModel):
@@ -35,6 +39,17 @@ class TextValue(BaseValue):
         if question.max_length and len(self.value) > question.max_length:
             raise ValueError(AnswerError.TOO_LONG.value)
 
+        if (
+            question.validator == form.TextValidator.tin
+            and validate_tin(self.value) is False
+        ):
+            raise ValueError(AnswerError.TIN_VALIDATION_FAILED.value)
+        if (
+            question.validator == form.TextValidator.snils
+            and validate_snils(self.value) is False
+        ):
+            raise ValueError(AnswerError.SNILS_VALIDATION_FAILED.value)
+
 
 class SelectorValue(BaseValue):
     question_type: form.QuestionType = form.QuestionType.selector
diff --git a/models/form.py b/models/form.py
index 01da847..400f5c7 100644
--- a/models/form.py
+++ b/models/form.py
@@ -21,6 +21,11 @@ class QuestionType(IntEnum):
     selector = 2
 
 
+class TextValidator(IntEnum):
+    tin = 1
+    snils = 2
+
+
 class BaseQuestion(BaseModel):
     id: UUID = Field(default_factory=uuid4)
     question_type: QuestionType
@@ -39,25 +44,33 @@ class Option(BaseModel):
 
 class TextQuestion(BaseQuestion):
     question_type: QuestionType = QuestionType.text
+    validator: TextValidator | None = None
     min_length: int | None = None
     max_length: int | None = None
 
     @field_validator("min_length")
     @classmethod
     def validate_min_length(cls, v, info):
-        if v is not None and v < 0:
-            raise ValueError(FormError.MIN_LENGTH_ERR.value)
+        validator = info.data.get("validator")
+        if v is not None:
+            if v < 0:
+                raise ValueError(FormError.MIN_LENGTH_ERR.value)
+            if validator is not None:
+                return None
         return v
 
     @field_validator("max_length")
     @classmethod
     def validate_max_length(cls, v, info):
         min_length = info.data.get("min_length")
+        validator = info.data.get("validator")
         if v is not None:
             if v <= 0:
                 raise ValueError(FormError.MAX_LENGTH_TOO_SMALL.value)
             if min_length is not None and v < min_length:
                 raise ValueError(FormError.MAX_LENGTH_LESS_THAN_MIN_LENGTH.value)
+            if validator is not None:
+                return None
         return v
 
 
@@ -89,9 +102,8 @@ class SelectorQuestion(BaseQuestion):
 Question: TypeAlias = SelectorQuestion | TextQuestion
 
 
-class FormData(BaseModel):
-    name: str = Field(min_length=1)
-    description: str | None = Field(None, min_length=1)
+class Page(BaseModel):
+    text: str | None = Field(None, min_length=1)
     questions: list[Question] = []
 
     @field_validator("questions")
@@ -107,6 +119,18 @@ class FormData(BaseModel):
         return v
 
 
+class FormData(BaseModel):
+    name: str = Field(min_length=1)
+    pages: list[Page] = []
+
+    @property
+    def questions(self) -> list[Question]:
+        questions = []
+        for page in self.pages:
+            questions.extend(page.questions)
+        return questions
+
+
 class Form(BaseModel):
     id: int
     data: FormData
diff --git a/utils/__init__.py b/utils/__init__.py
new file mode 100644
index 0000000..2c71abe
--- /dev/null
+++ b/utils/__init__.py
@@ -0,0 +1 @@
+from .validator import *
diff --git a/utils/validator.py b/utils/validator.py
new file mode 100644
index 0000000..e9fc4e2
--- /dev/null
+++ b/utils/validator.py
@@ -0,0 +1,76 @@
+def validate_tin(value: str) -> bool:
+    if len(value) != 10 and len(value) != 12:
+        return False
+
+    value = list(map(int, value))
+
+    if len(value) == 10:
+        checksum = (
+            (
+                2 * value[0]
+                + 4 * value[1]
+                + 10 * value[2]
+                + 3 * value[3]
+                + 5 * value[4]
+                + 9 * value[5]
+                + 4 * value[6]
+                + 6 * value[7]
+                + 8 * value[8]
+            )
+            % 11
+            % 10
+        )
+        return value[9] == checksum
+    if len(value) == 12:
+        checksum1 = (
+            (
+                7 * value[0]
+                + 2 * value[1]
+                + 4 * value[2]
+                + 10 * value[3]
+                + 3 * value[4]
+                + 5 * value[5]
+                + 9 * value[6]
+                + 4 * value[7]
+                + 6 * value[8]
+                + 8 * value[9]
+            )
+            % 11
+            % 10
+        )
+        checksum2 = (
+            (
+                3 * value[0]
+                + 7 * value[1]
+                + 2 * value[2]
+                + 4 * value[3]
+                + 10 * value[4]
+                + 3 * value[5]
+                + 5 * value[6]
+                + 9 * value[7]
+                + 4 * value[8]
+                + 6 * value[9]
+                + 8 * value[10]
+            )
+            % 11
+            % 10
+        )
+        return value[10] == checksum1 and value[11] == checksum2
+
+    return False
+
+
+def validate_snils(value: str) -> bool:
+    if len(value) == 11:
+        checksum = 0
+        for i in range(9):
+            checksum += int(value[i]) * (9 - i)
+
+        if checksum > 101:
+            checksum = checksum % 101
+        if checksum == 100 or checksum == 101:
+            checksum = 0
+
+        return checksum == int(value[9:])
+
+    return False