diff --git a/Invoice.java b/Invoice.java
new file mode 100644
index 000000000..4c28b4d5c
--- /dev/null
+++ b/Invoice.java
@@ -0,0 +1,79 @@
+package pl.edu.agh.mwo.invoice;
+
+import java.math.BigDecimal;
+import java.util.ArrayList;
+import java.util.Collection;
+
+import pl.edu.agh.mwo.invoice.product.Product;
+
+public class Invoice {
+	private Collection<Product> products;
+	private BigDecimal subTotal;
+	private BigDecimal total;
+	private BigDecimal tax;
+
+	
+	Invoice() {
+		subTotal = new BigDecimal("0");
+		total = new BigDecimal("0");
+		tax = new BigDecimal("0");
+		products = new ArrayList<Product>();
+
+	}
+
+	public void addProduct(Product product) {
+		products.add(product);
+		update();
+	}
+
+	public void addProduct(Product product, Integer quantity) {
+		if (quantity <= 0) {
+			throw new IllegalArgumentException();
+		}
+		for (int i = 0; i < quantity; i++) {
+			products.add(product);
+		}
+		update();
+	}
+	public BigDecimal getSubtotal() {
+		return subTotal;
+	}
+	public void setSubtotal() {
+		subTotal = BigDecimal.ZERO;
+		for (Product product : products) {
+			subTotal = subTotal.add(product.getPrice());
+		}
+	}
+
+	public BigDecimal getTax() {
+		return tax;
+	}
+	
+	public void setTax() {
+		tax = total.subtract(subTotal);
+	}
+
+	public BigDecimal getTotal() {
+		return total;
+	}
+	public void setTotal() {
+		total = BigDecimal.ZERO;
+		for (Product product : products) {
+			total = total.add(product.getPriceWithTax());
+		}
+	}
+
+	public static Invoice create() {
+		return new Invoice();
+	}
+
+	public void update() {
+		setSubtotal();
+		setTotal();
+		setTax();
+	}
+
+	
+
+}
+
diff --git a/Product.java b/Product.java
new file mode 100644
index 000000000..f42200be1
--- /dev/null
+++ b/Product.java
@@ -0,0 +1,37 @@
+public abstract class Product {
+	private final String name;
+
+	private final BigDecimal price;
+
+	private final BigDecimal taxPercent;
+
+	protected Product(String name, BigDecimal price, BigDecimal tax) {
+		if (name == null || name.equals("")) {
+			throw new IllegalArgumentException("Product name cannot be null");
+		} 
+		if (price == null || price.compareTo(BigDecimal.ZERO) < 0) {
+			throw new IllegalArgumentException("Product cannot be null");
+		}
+		this.name = name;
+		this.price = price;
+		this.taxPercent = tax;
+	}
+
+	public String getName() {
+		return name;
+	}
+
+	public BigDecimal getPrice() {
+		return price;
+	}
+
+	public BigDecimal getTaxPercent() {
+		return taxPercent;
+	}
+
+	public BigDecimal getPriceWithTax() {
+		return this.price.add(this.taxPercent.multiply(this.price));
+	}
+	
+}
+
diff --git a/java-invoice b/java-invoice
new file mode 160000
index 000000000..c9f6e9205
--- /dev/null
+++ b/java-invoice
@@ -0,0 +1 @@
+Subproject commit c9f6e92050237c5f2de729304ffcf85a826b8b57
diff --git a/src/test/java/pl/edu/agh/mwo/invoice/InvoiceTest.java b/src/test/java/pl/edu/agh/mwo/invoice/InvoiceTest.java
new file mode 100644
index 000000000..720f0c9a5
--- /dev/null
+++ b/src/test/java/pl/edu/agh/mwo/invoice/InvoiceTest.java
@@ -0,0 +1,107 @@
+package pl.edu.agh.mwo.invoice;
+
+import java.math.BigDecimal;
+
+import org.hamcrest.Matchers;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+import pl.edu.agh.mwo.invoice.Invoice;
+import pl.edu.agh.mwo.invoice.product.DairyProduct;
+import pl.edu.agh.mwo.invoice.product.OtherProduct;
+import pl.edu.agh.mwo.invoice.product.Product;
+import pl.edu.agh.mwo.invoice.product.TaxFreeProduct;
+
+public class InvoiceTest {
+	private Invoice invoice;
+
+	@Before
+	public void createEmptyInvoiceForTheTest() {
+		invoice = new Invoice();
+	}
+
+	@Test
+	public void testEmptyInvoiceHasEmptySubtotal() {
+		Assert.assertThat(BigDecimal.ZERO, Matchers.comparesEqualTo(invoice.getSubtotal()));
+	}
+
+	@Test
+	public void testEmptyInvoiceHasEmptyTaxAmount() {
+		Assert.assertThat(BigDecimal.ZERO, Matchers.comparesEqualTo(invoice.getTax()));
+	}
+
+	@Test
+	public void testEmptyInvoiceHasEmptyTotal() {
+		Assert.assertThat(BigDecimal.ZERO, Matchers.comparesEqualTo(invoice.getTotal()));
+	}
+
+	@Test
+	public void testInvoiceHasTheSameSubtotalAndTotalIfTaxIsZero() {
+		Product taxFreeProduct = new TaxFreeProduct("Warzywa", new BigDecimal("199.99"));
+		invoice.addProduct(taxFreeProduct);
+		Assert.assertThat(invoice.getTotal(), Matchers.comparesEqualTo(invoice.getSubtotal()));
+	}
+
+	@Test
+	public void testInvoiceHasProperSubtotalForManyProducts() {
+		invoice.addProduct(new TaxFreeProduct("Owoce", new BigDecimal("200")));
+		invoice.addProduct(new DairyProduct("Maslanka", new BigDecimal("100")));
+		invoice.addProduct(new OtherProduct("Wino", new BigDecimal("10")));
+		Assert.assertThat(new BigDecimal("310"), Matchers.comparesEqualTo(invoice.getSubtotal()));
+	}
+
+	@Test
+	public void testInvoiceHasProperTaxValueForManyProduct() {
+		// tax: 0
+		invoice.addProduct(new TaxFreeProduct("Pampersy", new BigDecimal("200")));
+		// tax: 8
+		invoice.addProduct(new DairyProduct("Kefir", new BigDecimal("100")));
+		// tax: 2.30
+		invoice.addProduct(new OtherProduct("Piwko", new BigDecimal("10")));
+		Assert.assertThat(new BigDecimal("10.30"), Matchers.comparesEqualTo(invoice.getTax()));
+	}
+
+	@Test
+	public void testInvoiceHasProperTotalValueForManyProduct() {
+		// price with tax: 200
+		invoice.addProduct(new TaxFreeProduct("Maskotki", new BigDecimal("200")));
+		// price with tax: 108
+		invoice.addProduct(new DairyProduct("Maslo", new BigDecimal("100")));
+		// price with tax: 12.30
+		invoice.addProduct(new OtherProduct("Chipsy", new BigDecimal("10")));
+		Assert.assertThat(new BigDecimal("320.30"), Matchers.comparesEqualTo(invoice.getTotal()));
+	}
+
+	@Test
+	public void testInvoiceHasPropoerSubtotalWithQuantityMoreThanOne() {
+		// 2x kubek - price: 10
+		invoice.addProduct(new TaxFreeProduct("Kubek", new BigDecimal("5")), 2);
+		// 3x kozi serek - price: 30
+		invoice.addProduct(new DairyProduct("Kozi Serek", new BigDecimal("10")), 3);
+		// 1000x pinezka - price: 10
+		invoice.addProduct(new OtherProduct("Pinezka", new BigDecimal("0.01")), 1000);
+		Assert.assertThat(new BigDecimal("50"), Matchers.comparesEqualTo(invoice.getSubtotal()));
+	}
+
+	@Test
+	public void testInvoiceHasPropoerTotalWithQuantityMoreThanOne() {
+		// 2x chleb - price with tax: 10
+		invoice.addProduct(new TaxFreeProduct("Chleb", new BigDecimal("5")), 2);
+		// 3x chedar - price with tax: 32.40
+		invoice.addProduct(new DairyProduct("Chedar", new BigDecimal("10")), 3);
+		// 1000x pinezka - price with tax: 12.30
+		invoice.addProduct(new OtherProduct("Pinezka", new BigDecimal("0.01")), 1000);
+		Assert.assertThat(new BigDecimal("54.70"), Matchers.comparesEqualTo(invoice.getTotal()));
+	}
+
+	@Test(expected = IllegalArgumentException.class)
+	public void testInvoiceWithZeroQuantity() {
+		invoice.addProduct(new TaxFreeProduct("Tablet", new BigDecimal("1678")), 0);
+	}
+
+	@Test(expected = IllegalArgumentException.class)
+	public void testInvoiceWithNegativeQuantity() {
+		invoice.addProduct(new DairyProduct("Zsiadle mleko", new BigDecimal("5.55")), -1);
+	}
+}
diff --git a/src/test/java/pl/edu/agh/mwo/invoice/product/ProductTest.java b/src/test/java/pl/edu/agh/mwo/invoice/product/ProductTest.java
new file mode 100644
index 000000000..832ae2c96
--- /dev/null
+++ b/src/test/java/pl/edu/agh/mwo/invoice/product/ProductTest.java
@@ -0,0 +1,57 @@
+package pl.edu.agh.mwo.invoice.product;
+
+import java.math.BigDecimal;
+
+import org.hamcrest.Matchers;
+import org.junit.Assert;
+import org.junit.Test;
+
+import pl.edu.agh.mwo.invoice.product.Product;
+
+public class ProductTest {
+	@Test
+	public void testProductNameIsCorrect() {
+		Product product = new OtherProduct("buty", new BigDecimal("100.0"));
+		Assert.assertEquals("buty", product.getName());
+	}
+
+	@Test
+	public void testProductPriceAndTaxWithDefaultTax() {
+		Product product = new OtherProduct("Ogorki", new BigDecimal("100.0"));
+		Assert.assertThat(new BigDecimal("100"), Matchers.comparesEqualTo(product.getPrice()));
+		Assert.assertThat(new BigDecimal("0.23"), Matchers.comparesEqualTo(product.getTaxPercent()));
+	}
+
+	@Test
+	public void testProductPriceAndTaxWithDairyProduct() {
+		Product product = new DairyProduct("Szarlotka", new BigDecimal("100.0"));
+		Assert.assertThat(new BigDecimal("100"), Matchers.comparesEqualTo(product.getPrice()));
+		Assert.assertThat(new BigDecimal("0.08"), Matchers.comparesEqualTo(product.getTaxPercent()));
+	}
+
+	@Test
+	public void testPriceWithTax() {
+		Product product = new DairyProduct("Oscypek", new BigDecimal("100.0"));
+		Assert.assertThat(new BigDecimal("108"), Matchers.comparesEqualTo(product.getPriceWithTax()));
+	}
+
+	@Test(expected = IllegalArgumentException.class)
+	public void testProductWithNullName() {
+		new OtherProduct(null, new BigDecimal("100.0"));
+	}
+
+	@Test(expected = IllegalArgumentException.class)
+	public void testProductWithEmptyName() {
+		new TaxFreeProduct("", new BigDecimal("100.0"));
+	}
+
+	@Test(expected = IllegalArgumentException.class)
+	public void testProductWithNullPrice() {
+		new DairyProduct("Banany", null);
+	}
+
+	@Test(expected = IllegalArgumentException.class)
+	public void testProductWithNegativePrice() {
+		new TaxFreeProduct("Mandarynki", new BigDecimal("-1.00"));
+	}
+}