diff --git a/lesson_17/bank/bank_app/src/main/java/com/codedifferently/lesson17/bank/Customer.java b/lesson_17/bank/bank_app/src/main/java/com/codedifferently/lesson17/bank/Customer.java
index af0847134..ca4e6ecd6 100644
--- a/lesson_17/bank/bank_app/src/main/java/com/codedifferently/lesson17/bank/Customer.java
+++ b/lesson_17/bank/bank_app/src/main/java/com/codedifferently/lesson17/bank/Customer.java
@@ -10,6 +10,7 @@ public class Customer {
   private final UUID id;
   private final String name;
   private final Set<CheckingAccount> accounts = new HashSet<>();
+  private boolean hasBusinessOwner;
 
   /**
    * Creates a new customer.
@@ -20,6 +21,7 @@ public class Customer {
   public Customer(UUID id, String name) {
     this.id = id;
     this.name = name;
+    this.hasBusinessOwner = false;
   }
 
   /**
@@ -71,6 +73,18 @@ public boolean equals(Object obj) {
     return false;
   }
 
+  public void changeToBusinessAccount() {
+    hasBusinessOwner = true;
+  }
+
+  public boolean hasBusinessOwner() {
+    return false;
+  }
+
+  public boolean getHasBusinessOwner() {
+    return true;
+  }
+
   @Override
   public String toString() {
     return "Customer{" + "id=" + id + ", name='" + name + '\'' + '}';
diff --git a/lesson_17/bank/bank_app/src/main/java/com/codedifferently/lesson17/bank/SavingAccount.java b/lesson_17/bank/bank_app/src/main/java/com/codedifferently/lesson17/bank/SavingAccount.java
new file mode 100644
index 000000000..66fe11508
--- /dev/null
+++ b/lesson_17/bank/bank_app/src/main/java/com/codedifferently/lesson17/bank/SavingAccount.java
@@ -0,0 +1,9 @@
+package com.codedifferently.lesson17.bank;
+
+import java.util.Set;
+
+public class SavingAccount extends CheckingAccount {
+  public SavingAccount(String accountNumber, Set<Customer> owners, double initialBalance) {
+    super(accountNumber, owners, initialBalance);
+  }
+}
diff --git a/lesson_17/bank/bank_app/src/main/java/com/codedifferently/lesson17/bank/exceptions/BusinessCheckingAccount.java b/lesson_17/bank/bank_app/src/main/java/com/codedifferently/lesson17/bank/exceptions/BusinessCheckingAccount.java
new file mode 100644
index 000000000..343941b8e
--- /dev/null
+++ b/lesson_17/bank/bank_app/src/main/java/com/codedifferently/lesson17/bank/exceptions/BusinessCheckingAccount.java
@@ -0,0 +1,25 @@
+package com.codedifferently.lesson17.bank.exceptions;
+
+import com.codedifferently.lesson17.bank.CheckingAccount;
+import com.codedifferently.lesson17.bank.Customer;
+import java.util.Set;
+
+public class BusinessCheckingAccount extends CheckingAccount {
+  public BusinessCheckingAccount(
+      String accountNumber, Set<Customer> owners, double initialBalance) {
+    super(accountNumber, owners, initialBalance);
+    if (!hasBusinessOwner(owners)) {
+      throw new IllegalArgumentException(
+          "A business account requires at least one owner to be a business.");
+    }
+  }
+
+  private boolean hasBusinessOwner(Set<Customer> owners) {
+    return owners.stream()
+        .anyMatch(
+            owner ->
+                owner.getName().toUpperCase().contains("INC")
+                    || owner.getName().toUpperCase().contains("LLC")
+                    || owner.getName().toUpperCase().contains("CO."));
+  }
+}
diff --git a/lesson_17/bank/bank_app/src/test/java/com/codedifferently/lesson17/bank/BusinessCheckingAccountTest.java b/lesson_17/bank/bank_app/src/test/java/com/codedifferently/lesson17/bank/BusinessCheckingAccountTest.java
new file mode 100644
index 000000000..d02df449a
--- /dev/null
+++ b/lesson_17/bank/bank_app/src/test/java/com/codedifferently/lesson17/bank/BusinessCheckingAccountTest.java
@@ -0,0 +1,57 @@
+package com.codedifferently.lesson17.bank;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+
+import com.codedifferently.lesson17.bank.exceptions.BusinessCheckingAccount;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.UUID;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+public class BusinessCheckingAccountTest {
+  private BusinessCheckingAccount classUnderTest;
+  private Set<Customer> owners;
+
+  @BeforeEach
+  void setUp() {
+    owners = new HashSet<>();
+  }
+
+  @Test
+  void testHasBusinessOwner_withINCInTheName() {
+    UUID id = UUID.randomUUID();
+    Customer businessOwner = new Customer(id, "Company INC");
+    owners.add(businessOwner);
+
+    BusinessCheckingAccount account = new BusinessCheckingAccount("123456", owners, 200);
+    assertNotNull(account);
+    assertEquals("123456", account.getAccountNumber());
+    assertEquals(200, account.getBalance());
+  }
+
+  @Test
+  void testHasBusinessOwner_withLLCInTheName() {
+    UUID id = UUID.randomUUID();
+    Customer businessOwner = new Customer(id, "Company ILLC");
+    owners.add(businessOwner);
+
+    BusinessCheckingAccount account = new BusinessCheckingAccount("123456", owners, 200);
+    assertNotNull(account);
+    assertEquals("123456", account.getAccountNumber());
+    assertEquals(200, account.getBalance());
+  }
+
+  @Test
+  void testHasBusinessOwner_withCOInTheName() {
+    UUID id = UUID.randomUUID();
+    Customer businessOwner = new Customer(id, "Company CO.");
+    owners.add(businessOwner);
+
+    BusinessCheckingAccount account = new BusinessCheckingAccount("123456", owners, 200);
+    assertNotNull(account);
+    assertEquals("123456", account.getAccountNumber());
+    assertEquals(200, account.getBalance());
+  }
+}
diff --git a/lesson_17/bank/bank_app/src/test/java/com/codedifferently/lesson17/bank/SavingAccountTest.java b/lesson_17/bank/bank_app/src/test/java/com/codedifferently/lesson17/bank/SavingAccountTest.java
new file mode 100644
index 000000000..536b10a8a
--- /dev/null
+++ b/lesson_17/bank/bank_app/src/test/java/com/codedifferently/lesson17/bank/SavingAccountTest.java
@@ -0,0 +1,105 @@
+package com.codedifferently.lesson17.bank;
+
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import com.codedifferently.lesson17.bank.exceptions.InsufficientFundsException;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.UUID;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+public class SavingAccountTest {
+  private SavingAccount classUnderTest;
+  private Set<Customer> owners;
+
+  @BeforeEach
+  void setUp() {
+    owners = new HashSet<>();
+    owners.add(new Customer(UUID.randomUUID(), "John Doe"));
+    owners.add(new Customer(UUID.randomUUID(), "Jane Smith"));
+    classUnderTest = new SavingAccount("123456789", owners, 100.0);
+  }
+
+  @Test
+  void getAccountNumber() {
+    assertEquals("123456789", classUnderTest.getAccountNumber());
+  }
+
+  @Test
+  void getOwners() {
+    assertEquals(owners, classUnderTest.getOwners());
+  }
+
+  @Test
+  void deposit() {
+    classUnderTest.deposit(50.0);
+    assertEquals(150.0, classUnderTest.getBalance());
+  }
+
+  @Test
+  void deposit_withNegativeAmount() {
+    assertThatExceptionOfType(IllegalArgumentException.class)
+        .isThrownBy(() -> classUnderTest.deposit(-50.0));
+  }
+
+  @Test
+  void withdraw() {
+    classUnderTest.withdraw(50.0);
+    assertEquals(50.0, classUnderTest.getBalance());
+  }
+
+  @Test
+  void withdraw_withNegativeAmount() {
+    assertThatExceptionOfType(IllegalStateException.class)
+        .isThrownBy(() -> classUnderTest.withdraw(-50.0))
+        .withMessage("Withdrawal amount must be positive");
+  }
+
+  @Test
+  void withdraw_withInsufficientBalance() {
+    assertThatExceptionOfType(InsufficientFundsException.class)
+        .isThrownBy(() -> classUnderTest.withdraw(150.0))
+        .withMessage("Account does not have enough funds for withdrawal");
+  }
+
+  @Test
+  void getBalance() {
+    assertEquals(100.0, classUnderTest.getBalance());
+  }
+
+  @Test
+  void closeAccount_withPositiveBalance() {
+    assertThatExceptionOfType(IllegalStateException.class)
+        .isThrownBy(() -> classUnderTest.closeAccount());
+  }
+
+  @Test
+  void isClosed() {
+    assertFalse(classUnderTest.isClosed());
+    classUnderTest.withdraw(100);
+    classUnderTest.closeAccount();
+    assertTrue(classUnderTest.isClosed());
+  }
+
+  @Test
+  void equals() {
+    SavingAccount otherAccount = new SavingAccount("123456789", owners, 200.0);
+    assertEquals(classUnderTest, otherAccount);
+  }
+
+  @Test
+  void hashCodeTest() {
+    SavingAccount otherAccount = new SavingAccount("123456789", owners, 200.0);
+    assertEquals(classUnderTest.hashCode(), otherAccount.hashCode());
+  }
+
+  @Test
+  void toStringTest() {
+    String expected = "CheckingAccount{accountNumber='123456789', balance=100.0, isActive=true}";
+    assertEquals(expected, classUnderTest.toString());
+  }
+}