Vbnet+billing+software+source+code !!exclusive!! [Verified × 2027]

Here’s an interesting, slightly opinionated review of VB.NET billing software source code — written from the perspective of a developer or small business owner evaluating such a solution.

2. Login Form (Login.vb)

Secure authentication using salt-hash (simplified here for demo).

Public Class LoginForm
    Private Sub btnLogin_Click(sender As Object, e As EventArgs) Handles btnLogin.Click
        Dim username As String = txtUsername.Text
        Dim password As String = txtPassword.Text
        Dim query As String = $"SELECT Role FROM tbl_Users WHERE Username='username' AND Password='password'"
        Dim dt As DataTable = ExecuteQuery(query)
    If dt.Rows.Count > 0 Then
        Dim role As String = dt.Rows(0)("Role").ToString()
        Dim mainForm As New MainDashboard(role, username)
        mainForm.Show()
        Me.Hide()
    Else
        MessageBox.Show("Invalid credentials!")
    End If
End Sub

End Class

Security Note: Never store plain passwords in production. Use SHA256 hashing.

1. Database Architecture (SQL Server)

Billing software is data-heavy. Look for a project that uses SQL Server (Express or Standard). The code should demonstrate:

Normalized tables (Customers, Products, Invoices, InvoiceDetails).
Stored Procedures for calculations (Sum, Tax, Discount) rather than doing it all in the UI code.

4.3. Invoice Generation Logic

The following code demonstrates the transaction process—inserting the invoice header and items, and updating stock atomically. vbnet+billing+software+source+code

Imports System.Data.SqlClient
Public Class InvoiceService
    Private dbHelper As New DatabaseHelper()
Public Function CreateInvoice(customerId As Integer, items As List(Of InvoiceItem)) As Boolean
        Dim queryInvoice As String = "INSERT INTO tbl_Invoices (Date, CustomerID, TotalAmount) VALUES (@Date, @CID, @Total); SELECT SCOPE_IDENTITY();"
        Dim queryItem As String = "INSERT INTO tbl_InvoiceItems (InvoiceID, ProductID, Quantity, UnitPrice) VALUES (@IID, @PID, @Qty, @Price);"
        Dim queryUpdateStock As String = "UPDATE tbl_Products SET StockQty = StockQty - @Qty WHERE ProductID = @PID;"
Using conn As SqlConnection = dbHelper.GetConnection()
            conn.Open()
            Dim transaction As SqlTransaction = conn.BeginTransaction()
Try
                Dim totalAmount As Decimal = items.Sum(Function(i) i.Total)
                Dim invoiceId As Integer
' 1. Insert Invoice Header
                Using cmd As New SqlCommand(queryInvoice, conn, transaction)
                    cmd.Parameters.AddWithValue("@Date", DateTime.Now)
                    cmd.Parameters.AddWithValue("@CID", customerId)
                    cmd.Parameters.AddWithValue("@Total", totalAmount)
                    invoiceId = Convert.ToInt32(cmd.ExecuteScalar())
                End Using
' 2. Insert Items and Update Stock
                For Each item In items
                    ' Insert Item
                    Using cmd As New SqlCommand(queryItem, conn, transaction)
                        cmd.Parameters.AddWithValue("@IID", invoiceId)
                        cmd.Parameters.AddWithValue("@PID", item.ProductID)
                        cmd.Parameters.AddWithValue("@Qty", item.Quantity)
                        cmd.Parameters.AddWithValue("@Price", item.UnitPrice)
                        cmd.ExecuteNonQuery()
                    End Using
' Update Stock
                    Using cmd As New SqlCommand(queryUpdateStock, conn, transaction)
                        cmd.Parameters.AddWithValue("@Qty", item.Quantity)
                        cmd.Parameters.AddWithValue("@PID", item.ProductID)
                        cmd.ExecuteNonQuery()
                    End Using
                Next
transaction.Commit()
                Return True
Catch ex As Exception
                transaction.Rollback()
                ' Log error
                Return False
            End Try
        End Using
    End Function
End Class

Where to Find Quality Source Code

If you are searching for "VB.NET billing software source code," be careful of "spaghetti code" repositories. Here are reliable places to look:

GitHub & CodeProject: Search specifically for "Inventory Management System VB.NET" rather than just "Billing." Billing is often a module within inventory systems.
SourceForge: A classic repository for older, open-source POS systems.
CodeMentor / Paid Repositories: Sometimes, paying $20–$50 for a professional template saves you 20 hours of debugging.

Step 4: Printing the Invoice (Using PrintDocument)

Add a PrintDocument and PrintPreviewDialog control to the form. Then handle the PrintPage event.

Private Sub btnPrint_Click(sender As Object, e As EventArgs) Handles btnPrint.Click
    PrintPreviewDialog1.Document = PrintDocument1
    PrintPreviewDialog1.ShowDialog()
End Sub
Private Sub PrintDocument1_PrintPage(sender As Object, e As Printing.PrintPageEventArgs) Handles PrintDocument1.PrintPage
Dim fontTitle As New Font("Arial", 18, FontStyle.Bold)
Dim fontBody As New Font("Arial", 10)
Dim yPos As Single = e.MarginBounds.Top
Dim leftMargin As Single = e.MarginBounds.Left Here’s an interesting, slightly opinionated review of  VB
e.Graphics.DrawString("TAX INVOICE", fontTitle, Brushes.Black, leftMargin, yPos)
yPos += 40
e.Graphics.DrawString("Invoice No: " & txtInvoiceNo.Text, fontBody, Brushes.Black, leftMargin, yPos)
yPos += 20
e.Graphics.DrawString("Date: " & txtInvoiceDate.Text, fontBody, Brushes.Black, leftMargin, yPos)
yPos += 30
' Draw headers
e.Graphics.DrawString("Item", fontBody, Brushes.Black, leftMargin, yPos)
e.Graphics.DrawString("Qty", fontBody, Brushes.Black, leftMargin + 200, yPos)
e.Graphics.DrawString("Rate", fontBody, Brushes.Black, leftMargin + 300, yPos)
e.Graphics.DrawString("Amount", fontBody, Brushes.Black, leftMargin + 400, yPos)
yPos += 20
For Each row As DataRow In dtDetails.Rows
    e.Graphics.DrawString(row("ProductName").ToString(), fontBody, Brushes.Black, leftMargin, yPos)
    e.Graphics.DrawString(row("Quantity").ToString(), fontBody, Brushes.Black, leftMargin + 200, yPos)
    e.Graphics.DrawString(row("Rate").ToString(), fontBody, Brushes.Black, leftMargin + 300, yPos)
    e.Graphics.DrawString(row("TaxableValue").ToString(), fontBody, Brushes.Black, leftMargin + 400, yPos)
    yPos += 20
Next
yPos += 20
e.Graphics.DrawString("Total: " & lblGrandTotal.Text, New Font("Arial", 12, FontStyle.Bold), Brushes.Black, leftMargin + 350, yPos)

End Sub

2. The "Transaction" Logic

This is where most amateur code fails. A billing system must be ACID compliant. When a customer clicks "Save Invoice," the code must: End Class

Deduct stock from the Inventory table.
Create the Invoice record.
Create the Invoice Line Items.
All within a Transaction Scope. If one part fails, the whole thing rolls back so your data doesn't get corrupted.