Vb.net Billing Software Source Code <2026>

Public Class Product
    Public Property ProductID As Integer
    Public Property ProductCode As String
    Public Property ProductName As String
    Public Property Category As String
    Public Property UnitPrice As Decimal
    Public Property StockQuantity As Integer
    Public Property GSTPercentage As Decimal
Public Function AddProduct() As Boolean
    Try
        Dim query As String = "INSERT INTO Products (ProductCode, ProductName, Category, UnitPrice, StockQuantity, GSTPercentage) VALUES (@Code, @Name, @Category, @Price, @Stock, @GST)"
        DBConnection.OpenConnection()
        Using cmd As New SqlCommand(query, DBConnection.conn)
            cmd.Parameters.AddWithValue("@Code", ProductCode)
            cmd.Parameters.AddWithValue("@Name", ProductName)
            cmd.Parameters.AddWithValue("@Category", Category)
            cmd.Parameters.AddWithValue("@Price", UnitPrice)
            cmd.Parameters.AddWithValue("@Stock", StockQuantity)
            cmd.Parameters.AddWithValue("@GST", GSTPercentage)
            Return cmd.ExecuteNonQuery() > 0
        End Using
    Catch ex As Exception
        MessageBox.Show("Error: " & ex.Message)
        Return False
    Finally
        DBConnection.CloseConnection()
    End Try
End Function
Public Shared Function GetAllProducts() As DataTable
    Dim dt As New DataTable()
    Try
        Dim query As String = "SELECT ProductID, ProductCode, ProductName, Category, UnitPrice, StockQuantity, GSTPercentage FROM Products"
        DBConnection.OpenConnection()
        Using adapter As New SqlDataAdapter(query, DBConnection.conn)
            adapter.Fill(dt)
        End Using
    Catch ex As Exception
        MessageBox.Show("Error: " & ex.Message)
    Finally
        DBConnection.CloseConnection()
    End Try
    Return dt
End Function

End Class

Imports System.Data.SqlClient
Public Class frmBilling
Private dtCart As New DataTable()
Private currentInvoiceNumber As String = ""
Private Sub frmBilling_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    InitializeCartTable()
    GenerateInvoiceNumber()
    LoadProducts()
    LoadCustomers()
End Sub
Private Sub InitializeCartTable()
    dtCart.Columns.Add("ProductID", GetType(Integer))
    dtCart.Columns.Add("ProductCode", GetType(String))
    dtCart.Columns.Add("ProductName", GetType(String))
    dtCart.Columns.Add("Quantity", GetType(Integer))
    dtCart.Columns.Add("UnitPrice", GetType(Decimal))
    dtCart.Columns.Add("GST", GetType(Decimal))
    dtCart.Columns.Add("Total", GetType(Decimal))
    dgvCart.DataSource = dtCart
    FormatDataGridView()
End Sub
Private Sub FormatDataGridView()
    dgvCart.Columns("ProductID").Visible = False
    dgvCart.Columns("ProductCode").HeaderText = "Product Code"
    dgvCart.Columns("ProductName").HeaderText = "Product Name"
    dgvCart.Columns("Quantity").HeaderText = "Qty"
    dgvCart.Columns("UnitPrice").HeaderText = "Unit Price"
    dgvCart.Columns("GST").HeaderText = "GST %"
    dgvCart.Columns("Total").HeaderText = "Total"
    dgvCart.AutoSizeColumnsMode = DataGridViewAutoSizeColumnsMode.Fill
End Sub
Private Sub GenerateInvoiceNumber()
    currentInvoiceNumber = "INV-" & DateTime.Now.ToString("yyyyMMdd") & "-" & DateTime.Now.ToString("HHmmss")
    txtInvoiceNo.Text = currentInvoiceNumber
End Sub
Private Sub LoadProducts()
    Try
        Dim dt As DataTable = Product.GetAllProducts()
        cmbProductName.DataSource = dt
        cmbProductName.DisplayMember = "ProductName"
        cmbProductName.ValueMember = "ProductID"
        cmbProductName.SelectedIndex = -1
    Catch ex As Exception
        MessageBox.Show("Error loading products: " & ex.Message)
    End Try
End Sub
Private Sub LoadCustomers()
    Try
        Dim query As String = "SELECT CustomerID, CustomerName FROM Customers"
        DBConnection.OpenConnection()
        Dim adapter As New SqlDataAdapter(query, DBConnection.conn)
        Dim dt As New DataTable()
        adapter.Fill(dt)
        cmbCustomer.DataSource = dt
        cmbCustomer.DisplayMember = "CustomerName"
        cmbCustomer.ValueMember = "CustomerID"
        DBConnection.CloseConnection()
    Catch ex As Exception
        MessageBox.Show("Error loading customers: " & ex.Message)
    End Try
End Sub
Private Sub cmbProductName_SelectedIndexChanged(sender As Object, e As EventArgs) Handles cmbProductName.SelectedIndexChanged
    If cmbProductName.SelectedValue IsNot Nothing Then
        Try
            Dim productID As Integer = Convert.ToInt32(cmbProductName.SelectedValue)
            Dim query As String = "SELECT ProductCode, UnitPrice, GSTPercentage FROM Products WHERE ProductID = @ProductID"
            DBConnection.OpenConnection()
            Using cmd As New SqlCommand(query, DBConnection.conn)
                cmd.Parameters.AddWithValue("@ProductID", productID)
                Using reader As SqlDataReader = cmd.ExecuteReader()
                    If reader.Read() Then
                        txtProductCode.Text = reader("ProductCode").ToString()
                        txtPrice.Text = reader("UnitPrice").ToString()
                        txtGST.Text = reader("GSTPercentage").ToString()
                        txtQuantity.Text = "1"
                        CalculateTotal()
                    End If
                End Using
            End Using
            DBConnection.CloseConnection()
        Catch ex As Exception
            MessageBox.Show("Error: " & ex.Message)
        End Try
    End If
End Sub
Private Sub CalculateTotal()
    If txtQuantity.Text <> "" And txtPrice.Text <> "" Then
        Dim quantity As Integer = Integer.Parse(txtQuantity.Text)
        Dim price As Decimal = Decimal.Parse(txtPrice.Text)
        Dim gst As Decimal = Decimal.Parse(txtGST.Text)
        Dim subtotal As Decimal = quantity * price
        Dim gstAmount As Decimal = subtotal * (gst / 100)
        Dim total As Decimal = subtotal + gstAmount
        txtSubtotal.Text = subtotal.ToString("N2")
        txtGSTAmount.Text = gstAmount.ToString("N2")
        txtTotal.Text = total.ToString("N2")
    End If
End Sub
Private Sub txtQuantity_TextChanged(sender As Object, e As EventArgs) Handles txtQuantity.TextChanged
    CalculateTotal()
End Sub
Private Sub btnAddToCart_Click(sender As Object, e As EventArgs) Handles btnAddToCart.Click
    If cmbProductName.SelectedValue Is Nothing Then
        MessageBox.Show("Please select a product")
        Return
    End If
Dim productID As Integer = Convert.ToInt32(cmbProductName.SelectedValue)
    Dim productCode As String = txtProductCode.Text
    Dim productName As String = cmbProductName.Text
    Dim quantity As Integer = Integer.Parse(txtQuantity.Text)
    Dim unitPrice As Decimal = Decimal.Parse(txtPrice.Text)
    Dim gst As Decimal = Decimal.Parse(txtGST.Text)
    Dim total As Decimal = Decimal.Parse(txtTotal.Text)
' Check if product already in cart
    Dim existingRow As DataRow() = dtCart.Select("ProductID = " & productID)
    If existingRow.Length > 0 Then
        existingRow(0)("Quantity") = CInt(existingRow(0)("Quantity")) + quantity
        existingRow(0)("Total") = CDec(existingRow(0)("Quantity")) * unitPrice
    Else
        dtCart.Rows.Add(productID, productCode, productName, quantity, unitPrice, gst, total)
    End If
UpdateGrandTotal()
    ClearProductFields()
End Sub
Private Sub UpdateGrandTotal()
    Dim grandTotal As Decimal = 0
    For Each row As DataRow In dtCart.Rows
        grandTotal += CDec(row("Total"))
    Next
    lblGrandTotal.Text = "Grand Total: ₹" & grandTotal.ToString("N2")
End Sub
Private Sub ClearProductFields()
    cmbProductName.SelectedIndex = -1
    txtProductCode.Clear()
    txtPrice.Clear()
    txtGST.Clear()
    txtQuantity.Clear()
    txtSubtotal.Clear()
    txtGSTAmount.Clear()
    txtTotal.Clear()
    txtQuantity.Text = "1"
End Sub
Private Sub btnRemoveFromCart_Click(sender As Object, e As EventArgs) Handles btnRemoveFromCart.Click
    If dgvCart.CurrentRow IsNot Nothing Then
        dtCart.Rows.RemoveAt(dgvCart.CurrentRow.Index)
        UpdateGrandTotal()
    End If
End Sub
Private Sub btnSaveInvoice_Click(sender As Object, e As EventArgs) Handles btnSaveInvoice.Click
    If dtCart.Rows.Count = 0 Then
        MessageBox.Show("Cart is empty!")
        Return
    End If
If cmbCustomer.SelectedValue Is Nothing Then
        MessageBox.Show("Please select a customer")
        Return
    End If
Try
        DBConnection.OpenConnection()
        Dim transaction As SqlTransaction = DBConnection.conn.BeginTransaction()
Try
            ' Calculate totals
            Dim subtotal As Decimal = 0
            Dim totalGST As Decimal = 0
            For Each row As DataRow In dtCart.Rows
                subtotal += CDec(row("Total"))
            Next
Dim totalAmount As Decimal = subtotal
' Insert Invoice
            Dim invoiceQuery As String = "INSERT INTO Invoices (InvoiceNumber, CustomerID, InvoiceDate, SubTotal, GSTAmount, TotalAmount, PaymentMethod, Status) VALUES (@InvoiceNo, @CustomerID, @Date, @SubTotal, @GST, @Total, @PaymentMethod, 'Completed') SELECT SCOPE_IDENTITY()"
Using cmd As New SqlCommand(invoiceQuery, DBConnection.conn, transaction)
                cmd.Parameters.AddWithValue("@InvoiceNo", txtInvoiceNo.Text)
                cmd.Parameters.AddWithValue("@CustomerID", Convert.ToInt32(cmbCustomer.SelectedValue))
                cmd.Parameters.AddWithValue("@Date", DateTime.Now)
                cmd.Parameters.AddWithValue("@SubTotal", subtotal)
                cmd.Parameters.AddWithValue("@GST", totalGST)
                cmd.Parameters.AddWithValue("@Total", totalAmount)
                cmd.Parameters.AddWithValue("@PaymentMethod", cmbPaymentMethod.Text)
Dim invoiceID As Integer = Convert.ToInt32(cmd.ExecuteScalar())
' Insert Invoice Items
                For Each row As DataRow In dtCart.Rows
                    Dim itemQuery As String = "INSERT INTO InvoiceItems (InvoiceID, ProductID, Quantity, UnitPrice, TotalPrice, GSTAmount) VALUES (@InvoiceID, @ProductID, @Quantity, @UnitPrice, @TotalPrice, @GSTAmount)"
                    Using itemCmd As New SqlCommand(itemQuery, DBConnection.conn, transaction)
                        itemCmd.Parameters.AddWithValue("@InvoiceID", invoiceID)
                        itemCmd.Parameters.AddWithValue("@ProductID", row("ProductID"))
                        itemCmd.Parameters.AddWithValue("@Quantity", row("Quantity"))
                        itemCmd.Parameters.AddWithValue("@UnitPrice", row("UnitPrice"))
                        itemCmd.Parameters.AddWithValue("@TotalPrice", row("Total"))
                        itemCmd.Parameters.AddWithValue("@GSTAmount", 0)
                        itemCmd.ExecuteNonQuery()
                    End Using
                Next
            End Using
transaction.Commit()
            MessageBox.Show("Invoice saved successfully! Invoice No: " & txtInvoiceNo.Text)
' Print receipt
            PrintReceipt()
' Reset form
            ResetForm()
Catch ex As Exception
            transaction.Rollback()
            MessageBox.Show("Error saving invoice: " & ex.Message)
        End Try
Catch ex As Exception
        MessageBox.Show("Database error: " & ex.Message)
    Finally
        DBConnection.CloseConnection()
    End Try
End Sub
Private Sub PrintReceipt()
    ' Simple print preview
    Dim printDialog As New PrintDialog()
    Dim printDocument As New Printing.PrintDocument()
AddHandler printDocument.PrintPage, AddressOf PrintDocument_PrintPage
printDialog.Document = printDocument
    If printDialog.ShowDialog() = DialogResult.OK Then
        printDocument.Print()
    End If
End Sub
Private Sub PrintDocument_PrintPage(sender As Object, e As Printing.PrintPageEventArgs)
    Dim font As New Font("Arial", 10)
    Dim titleFont As New Font("Arial", 14, FontStyle.Bold)
    Dim yPos As Single = 50
    Dim leftMargin As Single = 50
    Dim xPos As Single = leftMargin
' Print Header
    e.Graphics.DrawString("BILLING SYSTEM", titleFont, Brushes.Black, xPos, yPos)
    yPos += 30
    e.Graphics.DrawString("Invoice No: " & txtInvoiceNo.Text, font, Brushes.Black, xPos, yPos)
    yPos += 20
    e.Graphics.DrawString("Date: " & DateTime.Now.ToString(), font, Brushes.Black, xPos, yPos)
    yPos += 20
    e.Graphics.DrawString("Customer: " & cmbCustomer.Text, font, Brushes.Black, xPos, yPos)
    yPos += 30
' Print Column Headers
    e.Graphics.DrawString("Product", font, Brushes.Black, xPos, yPos)
    e.Graphics.DrawString("Qty", font, Brushes.Black, xPos + 150, yPos)
    e.Graphics.DrawString("Price", font, Brushes.Black, xPos + 250, yPos)
    e.Graphics.DrawString("Total", font, Brushes.Black, xPos + 350, yPos)
    yPos += 20
    e.Graphics.DrawLine(Pens.Black, leftMargin, yPos, 500, yPos)
    yPos += 10
' Print Items
    For Each row As DataRow In dtCart.Rows
        e.Graphics.DrawString(row("ProductName").ToString(), font, Brushes.Black, xPos, yPos)
        e.Graphics.DrawString(row("Quantity").ToString(), font, Brushes.Black, xPos + 150, yPos)
        e.Graphics.DrawString(CDec(row("UnitPrice")).ToString("N2"), font, Brushes.Black, xPos + 250, yPos)
        e.Graphics.DrawString(CDec(row("Total")).ToString("N2"), font, Brushes.Black, xPos + 350, yPos)
        yPos += 20
    Next
yPos += 10
    e.Graphics.DrawLine(Pens.Black, leftMargin, yPos, 500, yPos)
    yPos += 10
    e.Graphics.DrawString("Grand Total: " & lblGrandTotal.Text, titleFont, Brushes.Black, xPos, yPos)
End Sub
Private Sub ResetForm()
    dtCart.Clear()
    GenerateInvoiceNumber()
    UpdateGrandTotal()
    ClearProductFields()
    cmbCustomer.SelectedIndex = -1
    cmbPaymentMethod.SelectedIndex = -1
End Sub

End Class

Before examining the source code, we must define the scope. A minimum viable product (MVP) for billing software typically includes:

You might be thinking, “Why not start from a blank screen?” vb.net billing software source code

You could, but starting from scratch means reinventing the wheel. You’ll spend weeks just figuring out how to format invoice numbers or calculate tax brackets. By downloading or purchasing VB.NET billing source code, you get an instant MVP (Minimum Viable Product).

Here is what a good source code base gives you out of the box:

Instead of coding the database structure, you start with a working skeleton. Your job shifts from "plumbing" to "customizing." Public Class Product Public Property ProductID As Integer

Most VB.NET billing source code examples use either Microsoft SQL Server Express (free, robust) or MS Access (portable, simple). Below is a normalized schema for a professional system.

In the world of desktop application development, Visual Basic .NET (VB.NET) remains a surprisingly robust and efficient choice for building business applications, particularly billing and invoicing systems. Its rapid application development (RAD) environment, seamless integration with the .NET framework, and ease of database connectivity make it an ideal language for creating point-of-sale (POS) systems, retail billing software, and service invoicing tools.

If you are searching for "VB.NET billing software source code," you are likely looking to do one of three things: build a custom solution for your business, learn how billing logic works under the hood, or modify an open-source project to fit specific needs. End Class

This article will serve as a deep dive into the architecture, features, database design, and actual code structure of a professional billing software built with VB.NET.

When you download or build "VB.NET billing software source code," the Visual Studio solution will look like this: