diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..c41cc9e
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+/target
\ No newline at end of file
diff --git a/pom.xml b/pom.xml
new file mode 100644
index 0000000..175e6bb
--- /dev/null
+++ b/pom.xml
@@ -0,0 +1,59 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>com.pfefferminzia</groupId>
+    <artifactId>pet-insurance</artifactId>
+    <version>1.0-SNAPSHOT</version>
+
+    <properties>
+        <maven.compiler.release>25</maven.compiler.release>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        
+        <junit.jupiter.version>5.11.4</junit.jupiter.version>
+        <maven.compiler.plugin.version>3.13.0</maven.compiler.plugin.version>
+        <maven.surefire.plugin.version>3.5.2</maven.surefire.plugin.version>
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <version>${junit.jupiter.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-engine</artifactId>
+            <version>${junit.jupiter.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-params</artifactId>
+            <version>${junit.jupiter.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>${maven.compiler.plugin.version}</version>
+                <configuration>
+                    <release>${maven.compiler.release}</release>
+                </configuration>
+            </plugin>
+            
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-surefire-plugin</artifactId>
+                <version>${maven.surefire.plugin.version}</version>
+            </plugin>
+        </plugins>
+    </build>
+</project>
\ No newline at end of file
diff --git a/src/test/java/com/pfefferminzia/petinsurance/calculations/CalculationsTest.java b/src/test/java/com/pfefferminzia/petinsurance/calculations/CalculationsTest.java
new file mode 100644
index 0000000..52fd31a
--- /dev/null
+++ b/src/test/java/com/pfefferminzia/petinsurance/calculations/CalculationsTest.java
@@ -0,0 +1,175 @@
+package com.pfefferminzia.petinsurance.calculations;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.fail;
+import java.math.BigDecimal;
+import java.time.LocalDate;
+import java.util.List;
+import java.util.stream.Stream;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+import com.pfefferminzia.petinsurance.animals.Animal;
+import com.pfefferminzia.petinsurance.animals.Cat;
+import com.pfefferminzia.petinsurance.animals.Dog;
+import com.pfefferminzia.petinsurance.animals.SmallAnimal;
+import com.pfefferminzia.petinsurance.exception.InvalidInsuranceContractException;
+import com.pfefferminzia.petinsurance.tariffs.TariffConfiguration;
+import com.pfefferminzia.petinsurance.tariffs.TariffLoader;
+
+class CalculationsTest {
+    private static Calculations calculationsEngine;
+
+    @BeforeAll
+    static void setUp() {
+        TariffConfiguration tariffConfig = TariffLoader.loadFromFile();
+        calculationsEngine = new Calculations(tariffConfig);
+    }
+
+    static Stream<Arguments> dogBreedPremiumCases() {
+        return Stream.of(Arguments.of("Husky", new BigDecimal("3500"), new BigDecimal("980")),
+                Arguments.of("Dackel", new BigDecimal("3500"), new BigDecimal("882")),
+                Arguments.of("Bernhardiner", new BigDecimal("3500"), new BigDecimal("1078")));
+    }
+
+    @ParameterizedTest
+    @MethodSource("dogBreedPremiumCases")
+    void shouldCalculateCorrectlyForDogSevenYearsAndPremiumTariff(String breed,
+            BigDecimal expectedSum, BigDecimal expectedPremium) {
+
+        Animal dog = new Dog(LocalDate.of(2019, 8, 1), breed);
+        InsuranceContract contract =
+                new InsuranceContract(dog, LocalDate.of(2026, 8, 1), "PREMIUM");
+
+        CalculationResult result =
+                calculationsEngine.calculateInsuranceSumAndYearlyPremium(contract);
+
+        assertBigDecimalEquals(expectedSum, result.insuranceSum());
+        assertBigDecimalEquals(expectedPremium, result.yearlyPremium());
+    }
+
+    @Test
+    void shouldCalculateCorrectlyForCatThreeYearsAndOptimalTariff() {
+        Animal cat = new Cat(LocalDate.of(2023, 8, 1));
+        InsuranceContract contract =
+                new InsuranceContract(cat, LocalDate.of(2026, 8, 1), "OPTIMAL");
+
+        CalculationResult result =
+                calculationsEngine.calculateInsuranceSumAndYearlyPremium(contract);
+
+        assertBigDecimalEquals(new BigDecimal("2400"), result.insuranceSum());
+        assertBigDecimalEquals(new BigDecimal("600"), result.yearlyPremium());
+    }
+
+    @Test
+    void shouldCalculateCorrectlyForSmallAnimalOneYearAndKompaktTariff() {
+        Animal smallAnimal = new SmallAnimal(LocalDate.of(2025, 8, 1));
+        InsuranceContract contract =
+                new InsuranceContract(smallAnimal, LocalDate.of(2026, 8, 1), "KOMPAKT");
+
+        CalculationResult result =
+                calculationsEngine.calculateInsuranceSumAndYearlyPremium(contract);
+
+        assertBigDecimalEquals(new BigDecimal("1000"), result.insuranceSum());
+        assertBigDecimalEquals(new BigDecimal("200"), result.yearlyPremium());
+    }
+
+    static Stream<Arguments> ageBracketCases() {
+        return Stream.of(
+                Arguments.of(2, new BigDecimal("200")),  // exactly at ≤2 boundary → factor 0.20
+                Arguments.of(3, new BigDecimal("250")),  // one above ≤2 boundary  → factor 0.25
+                Arguments.of(5, new BigDecimal("250")),  // exactly at ≤5 boundary → factor 0.25
+                Arguments.of(6, new BigDecimal("280")),  // one above ≤5 boundary  → factor 0.28
+                Arguments.of(7, new BigDecimal("280")),  // exactly at ≤7 boundary → factor 0.28
+                Arguments.of(8, new BigDecimal("300"))   // one above ≤7 boundary  → factor 0.30
+        );
+    }
+
+    @ParameterizedTest(name = "age {0} → premium {1}")
+    @MethodSource("ageBracketCases")
+    void shouldApplyCorrectAgeFactorAtEachBracketBoundary(int age, BigDecimal expectedPremium) {
+        LocalDate startDate = LocalDate.of(2026, 8, 1);
+        Animal animal = new SmallAnimal(startDate.minusYears(age));
+        InsuranceContract contract = new InsuranceContract(animal, startDate, "KOMPAKT");
+
+        CalculationResult result =
+                calculationsEngine.calculateInsuranceSumAndYearlyPremium(contract);
+
+        assertBigDecimalEquals(expectedPremium, result.yearlyPremium());
+    }
+
+    @Test
+    void shouldThrowExceptionWhenPremiumTariffIsSelectedBeforeJulyFirst() {
+        Animal dog = new Dog(LocalDate.of(2019, 8, 1), "Schäferhund");
+        InsuranceContract contract =
+                new InsuranceContract(dog, LocalDate.of(2026, 2, 1), "PREMIUM");
+
+        assertThrows(IllegalStateException.class,
+                () -> calculationsEngine.calculateInsuranceSumAndYearlyPremium(contract));
+    }
+
+    @Test
+    void shouldReportViolationWhenAnimalIsNull() {
+        LocalDate insuranceStart = LocalDate.of(2026, 8, 1);
+
+        InvalidInsuranceContractException ex = assertThrows(InvalidInsuranceContractException.class,
+                () -> new InsuranceContract(null, insuranceStart, "KOMPAKT"));
+
+        assertEquals(List.of("Animal darf nicht leer sein"), ex.getViolations());
+    }
+
+    @Test
+    void shouldReportViolationWhenTariffNameIsNull() {
+        Animal animal = new Cat(LocalDate.of(2023, 8, 1));
+        LocalDate insuranceStart = LocalDate.of(2026, 8, 1);
+
+
+        InvalidInsuranceContractException ex = assertThrows(InvalidInsuranceContractException.class,
+                () -> new InsuranceContract(animal, insuranceStart, null));
+
+        assertEquals(List.of("Tarif darf nicht leer sein"), ex.getViolations());
+    }
+
+    @Test
+    void shouldReportViolationWhenInsuranceStartDateIsNull() {
+        Animal animal = new Cat(LocalDate.of(2023, 8, 1));
+
+        InvalidInsuranceContractException ex = assertThrows(InvalidInsuranceContractException.class,
+                () -> new InsuranceContract(animal, null, "KOMPAKT"));
+
+        assertEquals(List.of("Versicherungsstart darf nicht leer sein"), ex.getViolations());
+    }
+
+    @Test
+    void shouldReportViolationWhenBirthdayIsAfterContractStart() {
+        Animal animal = new Cat(LocalDate.of(2026, 8, 1));
+        LocalDate insuranceStart = LocalDate.of(2026, 2, 1);
+
+        InvalidInsuranceContractException ex = assertThrows(InvalidInsuranceContractException.class,
+                () -> new InsuranceContract(animal, insuranceStart, "KOMPAKT"));
+
+        assertEquals(List.of("Start der Versicherung kann nicht vor dem Geburtstag sein."),
+                ex.getViolations());
+    }
+
+    @Test
+    void shouldCollectAllViolationsWhenMultipleFieldsAreInvalid() {
+        InvalidInsuranceContractException ex = assertThrows(InvalidInsuranceContractException.class,
+                () -> new InsuranceContract(null, null, null));
+
+        assertEquals(
+                List.of("Animal darf nicht leer sein", "Tarif darf nicht leer sein",
+                        "Versicherungsstart darf nicht leer sein"),
+                ex.getViolations());
+    }
+
+    private void assertBigDecimalEquals(BigDecimal expected, BigDecimal actual) {
+        if (expected.compareTo(actual) != 0) {
+            fail(String.format("Expected: <%s> but is: <%s>", expected.toPlainString(),
+                    actual.toPlainString()));
+        }
+    }
+}
diff --git a/src/test/resources/tariff.properties b/src/test/resources/tariff.properties
new file mode 100644
index 0000000..74dd508
--- /dev/null
+++ b/src/test/resources/tariff.properties
@@ -0,0 +1,20 @@
+
+# Animal base insurance sums: species=baseSum
+baseSum.DOG=2500.00
+baseSum.CAT=2000.00
+baseSum.SMALLANIMAL=1000.00
+
+# Tariffs: name=factor,availableFromDate
+tariffs.KOMPAKT=1.0,1970-01-01
+tariffs.OPTIMAL=1.2,1970-01-01
+tariffs.PREMIUM=1.4,2026-07-01
+
+# Age tariffs factor: age=factor
+age.2=0.20
+age.5=0.25
+age.7=0.28
+elderlyFactor=0.30
+
+# Dog breed premium factor: breed=factor
+breed.DACKEL=-0.1
+breed.BERNHARDINER=0.1
\ No newline at end of file