diff --git a/JCash.iml b/JCash.iml
new file mode 100644
index 0000000..c90834f
--- /dev/null
+++ b/JCash.iml
@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>
\ No newline at end of file
diff --git a/src/Main.java b/src/Main.java
new file mode 100644
index 0000000..3e59c38
--- /dev/null
+++ b/src/Main.java
@@ -0,0 +1,5 @@
+public class Main {
+    public static void main(String[] args) {
+        System.out.println("Hello world!");
+    }
+}
\ No newline at end of file
diff --git a/src/me/teridax/jcash/banking/Account.java b/src/me/teridax/jcash/banking/Account.java
new file mode 100644
index 0000000..36b534a
--- /dev/null
+++ b/src/me/teridax/jcash/banking/Account.java
@@ -0,0 +1,34 @@
+package me.teridax.jcash.banking;
+
+@SuppressWarnings("unused")
+public abstract class Account {
+
+    private int iban;
+    private int pin;
+    private double balance;
+
+    private final Owner owner;
+
+    public Account(int iban, int pin, Owner owner) {
+        this.owner = owner;
+        this.iban = iban;
+        this.pin = pin;
+        this.balance = 0.0d;
+    }
+
+    public Owner getOwner() {
+        return owner;
+    }
+
+    public int getIban() {
+        return iban;
+    }
+
+    public int getPin() {
+        return pin;
+    }
+
+    public double getBalance() {
+        return balance;
+    }
+}
diff --git a/src/me/teridax/jcash/banking/Bank.java b/src/me/teridax/jcash/banking/Bank.java
new file mode 100644
index 0000000..026b5d5
--- /dev/null
+++ b/src/me/teridax/jcash/banking/Bank.java
@@ -0,0 +1,61 @@
+package me.teridax.jcash.banking;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
+
+@SuppressWarnings("unused")
+public final class Bank {
+    private String name;
+    private int blz;
+    private List<Account> accounts;
+
+    private Bank(int blz, String name) {
+        this.blz = blz;
+        this.name = name;
+        this.accounts = new ArrayList<>();
+    }
+
+    public Account[] getAccounts() {
+        return accounts.toArray(new Account[0]);
+    }
+
+    public int getBlz() {
+        return blz;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (obj instanceof Bank) {
+            return blz == ((Bank) obj).blz;
+        }
+        return false;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(blz, name);
+    }
+
+    public Account[] getAccountsOfOwner(Owner owner) {
+        return accounts.stream()
+              .filter(account -> account.getOwner().equals(owner))
+              .toArray(Account[]::new);
+    }
+
+    private static String validateBlz(String maybeBlz) {
+        var builder = new StringBuilder();
+        maybeBlz.trim().chars().filter(ch -> Character.isDigit(ch) || Character.isLetter(ch)).forEach(builder::append);
+        var blz = builder.toString();
+
+        if (blz.isEmpty()) {
+            throw new IllegalArgumentException("Bank Blz must only contain letters and digits");
+        }
+
+        return blz;
+    }
+}
diff --git a/src/me/teridax/jcash/banking/BankingManagementSystem.java b/src/me/teridax/jcash/banking/BankingManagementSystem.java
new file mode 100644
index 0000000..1cd09ae
--- /dev/null
+++ b/src/me/teridax/jcash/banking/BankingManagementSystem.java
@@ -0,0 +1,35 @@
+package me.teridax.jcash.banking;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.util.ArrayList;
+import java.util.List;
+
+public final class BankingManagementSystem {
+
+    private List<Bank> banks;
+
+    private BankingManagementSystem(List<Bank> banks) {
+        this.banks = banks;
+    }
+
+    public static BankingManagementSystem loadFromCsv(File file) {
+
+        try {
+            var content = Files.readString(file.toPath());
+
+            var banks = new ArrayList<Bank>();
+
+            content.lines().forEach(line -> {
+                // load bank and account from line.
+                // transfer accounts to existing bank if already created
+            });
+
+        } catch (IOException e) {
+            throw new IllegalArgumentException("Could not read file " + file);
+        }
+
+        return null;
+    }
+}
diff --git a/src/me/teridax/jcash/banking/Girokonto.java b/src/me/teridax/jcash/banking/Girokonto.java
new file mode 100644
index 0000000..68ba9f5
--- /dev/null
+++ b/src/me/teridax/jcash/banking/Girokonto.java
@@ -0,0 +1,15 @@
+package me.teridax.jcash.banking;
+
+public class Girokonto extends Account {
+
+    private double overdraft;
+
+    public Girokonto(int iban, int pin, double overdraft, Owner owner) {
+        super(iban, pin, owner);
+        this.overdraft = overdraft;
+    }
+
+    public double getOverdraft() {
+        return overdraft;
+    }
+}
diff --git a/src/me/teridax/jcash/banking/Owner.java b/src/me/teridax/jcash/banking/Owner.java
new file mode 100644
index 0000000..1f337e8
--- /dev/null
+++ b/src/me/teridax/jcash/banking/Owner.java
@@ -0,0 +1,66 @@
+package me.teridax.jcash.banking;
+
+import java.util.Objects;
+
+@SuppressWarnings("unused")
+public final class Owner {
+    private int uid;
+    private String familyName;
+    private String name;
+    private String street;
+    private int zip;
+    private String city;
+
+    private Owner() { }
+
+    public Owner(int uid, String familyName, String name, int zip, String city, String street) {
+        this.uid = uid;
+        this.familyName = familyName;
+        this.name = name;
+        this.zip = zip;
+        this.city = city;
+        this.street = street;
+    }
+
+    public long getUid() {
+        return uid;
+    }
+
+    public String getFamilyName() {
+        return familyName;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public int getZip() {
+        return zip;
+    }
+
+    public String getCity() {
+        return city;
+    }
+
+    public String getStreet() {
+        return street;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(uid, familyName, name, zip, city, street);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (obj instanceof Owner) {
+            return this.uid == ((Owner) obj).getUid();
+        }
+        return false;
+    }
+
+    @Override
+    public String toString() {
+        return String.format("@Owner[uid=%08x, familyName=%s, name=%s, zip=%s, city=%s, street=%s]", uid, familyName, name, zip, city, street);
+    }
+}
diff --git a/src/me/teridax/jcash/banking/SavingsAccount.java b/src/me/teridax/jcash/banking/SavingsAccount.java
new file mode 100644
index 0000000..7e36c58
--- /dev/null
+++ b/src/me/teridax/jcash/banking/SavingsAccount.java
@@ -0,0 +1,16 @@
+package me.teridax.jcash.banking;
+
+@SuppressWarnings("unused")
+public class SavingsAccount extends Account {
+
+    private double interest;
+
+    public SavingsAccount(int iban, int pin, double interest, Owner owner) {
+        super(iban, pin, owner);
+        this.interest = interest;
+    }
+
+    public double getInterest() {
+        return interest;
+    }
+}
diff --git a/src/me/teridax/jcash/decode/Decoder.java b/src/me/teridax/jcash/decode/Decoder.java
new file mode 100644
index 0000000..66542f1
--- /dev/null
+++ b/src/me/teridax/jcash/decode/Decoder.java
@@ -0,0 +1,118 @@
+package me.teridax.jcash.decode;
+
+import org.junit.Test;
+
+import java.text.NumberFormat;
+import java.text.ParseException;
+import java.util.Locale;
+import java.util.Objects;
+import java.util.regex.Pattern;
+
+import static junit.framework.TestCase.assertEquals;
+
+public class Decoder {
+
+    private static final Locale LOCALE = Locale.GERMANY;
+    private static final NumberFormat LOCAL_NUMBER_FORMAT = NumberFormat.getInstance(LOCALE);
+
+    public static double decodePercent(String number) throws IllegalArgumentException, NullPointerException {
+        Objects.requireNonNull(number);
+
+        // trim the number and cut out optional percent symbols
+        var trimmed = number.trim().replace("%", "");
+
+        try {
+            return LOCAL_NUMBER_FORMAT.parse(trimmed).doubleValue();
+        } catch (ParseException ex) {
+            throw new IllegalArgumentException("Not a valid number: " + number, ex);
+        }
+    }
+
+    public static double decodeCurrency(String currency) throws IllegalArgumentException, NullPointerException {
+        Objects.requireNonNull(currency);
+
+        try {
+            return LOCAL_NUMBER_FORMAT.parse(currency.trim()).doubleValue();
+        } catch (ParseException ex) {
+            throw new IllegalArgumentException("Not a valid currency in german locale: " + currency, ex);
+        }
+    }
+
+    public static int decodeSerialNumber(String number) throws IllegalArgumentException, NullPointerException {
+        Objects.requireNonNull(number);
+
+        // check if the string is a valid unsigned number
+        try {
+            LOCAL_NUMBER_FORMAT.setParseIntegerOnly(true);
+            var serialNumber = LOCAL_NUMBER_FORMAT.parse(number.trim());
+            LOCAL_NUMBER_FORMAT.setParseIntegerOnly(false);
+            return serialNumber.intValue();
+        } catch (ParseException ex) {
+            throw new IllegalArgumentException("Not a valid serial number: " + number, ex);
+        }
+    }
+
+    public static String decodeName(String name) throws IllegalArgumentException, NullPointerException {
+        Objects.requireNonNull(name);
+
+        var trimmed = name.trim();
+
+        // check if the string is a valid unsigned number
+        if (!trimmed.trim().chars().allMatch(Character::isLetter))
+            throw new IllegalArgumentException("Not a valid name: " + name);
+
+        return trimmed;
+    }
+
+    public static String decodeStreet(String street) throws IllegalArgumentException, NullPointerException {
+        Objects.requireNonNull(street);
+
+        var pattern = Pattern.compile("\\S+(\\s+\\d+(/\\d+)?)?", Pattern.CASE_INSENSITIVE);
+        var matcher = pattern.matcher(street);
+        if (matcher.find()) {
+            return matcher.group();
+        } else {
+            throw new IllegalArgumentException("not a void address");
+        }
+    }
+
+    @Test
+    public void testDecodeSuccessfulFunctions() {
+        decodeSerialNumber("95786978625347895");
+        decodeSerialNumber("    927856347   ");
+        decodeSerialNumber("0");
+
+        decodeName("Adolf");
+        decodeName("Günther");
+        decodeName("Saßkia");
+
+        decodeStreet("Bahnhofstraße 40/1");
+        decodeStreet("Gülleweg 9");
+        decodeStreet("Echsengaße 67 / 4");
+
+        assertEquals(decodePercent("1,4%"), 1.4d);
+        assertEquals(decodePercent("99"), 99.0d);
+        assertEquals(decodePercent("1,003  %"), 1.003d);
+
+        assertEquals(decodeCurrency("1,3€"), 1.3d);
+        assertEquals(decodeCurrency("145,34"), 145,34d);
+        assertEquals(decodeCurrency("0,45   €"), 0.45d);
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testDecodeInvalidFunctions() {
+        decodeSerialNumber("q0948tvb6q047t 740   t74z0tz    784");
+        decodeSerialNumber("-39867.8475");
+        decodeSerialNumber("-398678475");
+        decodeSerialNumber(" ß9qu908t76q34798t6q734vb9843");
+
+        decodeName("John Doe");
+        decodeName("3490qt67v 0b34");
+        decodeName("Alexander9");
+        decodeName("-ga76re78g6$§");
+
+        decodeStreet("Bahnhofstraße -40/1");
+        decodeStreet("Gülleweg 9//567");
+        decodeStreet("23Echsengaße 67 / 4 Hofwetg 9");
+    }
+}