Simple Billing - GST Billing Software User Guide

Developed by: PSP Softech
Email: support@pspsoft.tech
Website: pspsoft.tech
Phone: +91 8902391021
Version: 1.0.0
Year: 2026

Introduction

Simple Billing is a powerful, offline-first GST billing and business management desktop software developed by PSP Softech. It is designed for Indian small and medium businesses (SMBs) who need a fast, reliable, and GST-compliant billing solution without internet dependency.

Simple Billing runs entirely on your computer — your data never leaves your machine unless you explicitly back it up. It supports all major GST features including GSTR-1 export, HSN/SAC code management, ITC tracking, and more.

Key Highlights

Feature	Description
Offline First	Works 100% without internet. No cloud subscription required.
GST Compliant	Full GST support — CGST, SGST, IGST, HSN codes, GSTR-1 export.
All-in-One	Sales, Purchase, Inventory, Payments, Reports — everything in one app.
White Label	Reseller-friendly — can be customised with your own branding.
Secure Licensing	Hardware-locked license with online verification and grace period.
PDF & WhatsApp	Send invoices as PDF via WhatsApp or Email directly from the app.

Getting Started

System Requirements

Feature	Description
Operating System	Windows 10 or Windows 11 (64-bit)
RAM	Minimum 4 GB (8 GB recommended)
Disk Space	Minimum 500 MB free space
Internet	Required only for license activation and WhatsApp/Email sending
Display	1280×720 or higher resolution

Installation

Run the Simple Billing Setup.exe installer.
Choose your installation directory (default: C:\Program Files\Simple Billing).
Click Install and wait for the installation to complete.
Launch Simple Billing from the Desktop shortcut or Start Menu.

License Activation

On first launch, you will see the License Activation screen.
Enter the license key provided by PSP Softech (format: XXXX-XXXX-XXXX-XXXX).
Click Activate License. The software will verify your license online.
Once activated, the license is locked to your device.
The software works offline for up to 7 days after the last online verification.
To renew your license, go to Settings → License and enter your new key.

Initial Setup — Company Profile

After activation, set up your company profile before creating invoices.
Go to Settings → Company Profile.
Fill in Business Name, GSTIN, PAN, Address, City, State, Pincode.
Add your Bank Details (Name, Account Number, IFSC, Branch).
Set your Invoice Prefix (e.g., INV) and Financial Year.
Click Save Company Profile.

📊 Module 1: Dashboard

The Dashboard is the home screen of Simple Billing. It gives you a real-time overview of your business at a glance.

Feature	Description
Today's Sales	Total invoice amount created today. Shows count of total invoices.
Total Customers	Number of active customers in your database.
Pending Dues	Total outstanding amount from unpaid and partially paid invoices.
Low Stock Items	Count of products where current stock is at or below minimum stock level.
Monthly Sales Chart	Bar chart showing month-wise sales for the current financial year.
Quick Actions	One-click buttons to create New Invoice, Add Customer, Add Product, Record Payment.
Total Sales	Lifetime total sales amount (all time).
Outstanding Dues	Current total outstanding amount across all customers.
Recent Invoices	Last 5 invoices with invoice number, date, customer, amount, and status. Click any row to view details.

👥 Module 2: Customer Management

Manage all your customers — their contact details, GSTIN, credit limits, and transaction history.

Feature	Description
Add Customer	Create a new customer with full details.
Edit Customer	Update any customer information at any time.
Delete Customer	Soft-delete a customer (data is preserved).
Search	Search customers by name, phone number, or GSTIN in real time.
Customer Name	Required field. Full business or individual name.
GSTIN	Customer's 15-digit GST Identification Number for B2B invoices.
PAN	Customer's Permanent Account Number.
Phone & Email	Contact details for WhatsApp and Email communication.
Address	Full address with city, state, state code (auto-filled), and pincode.
Credit Limit	Set maximum credit amount for this customer.
Notes	Internal notes about the customer.

How to Add a Customer

Click Customers in the left menu.
Click + Add Customer (top right).
Fill in the customer details. GSTIN and State will auto-fill State Code.
Click Add Customer to save.

🏭 Module 3: Supplier Management

Manage all your suppliers from whom you purchase goods or services.

Feature	Description
Add Supplier	Create a new supplier with full business details.
Edit Supplier	Update supplier information at any time.
Delete Supplier	Soft-delete a supplier.
Search	Search suppliers by name, phone, or GSTIN.
GSTIN	Supplier's GSTIN for ITC (Input Tax Credit) claims.
Full Address	City, State, State Code (auto-filled), Pincode.
Notes	Internal notes about the supplier.

📦 Module 4: Product & Inventory Management

Manage your product catalog with pricing, HSN codes, tax rates, and real-time stock tracking.

Feature	Description
Add Product	Create a new product or service with full details.
Edit Product	Update product information including price and tax rate.
Delete Product	Soft-delete a product.
Search	Search products by name or HSN code.
HSN / SAC Code	Harmonised System of Nomenclature or Service Accounting Code for GST filing.
Unit	Unit of measurement — PCS, KG, GM, LTR, ML, MTR, BOX, DOZEN, PAIR, etc.
Purchase Price	Your buying cost — used for P&L calculation.
Sale Price	Default selling price — auto-filled in invoices.
MRP	Maximum Retail Price for reference.
GST Rate	Tax rate — 0%, 0.25%, 3%, 5%, 12%, 18%, or 28%.
Opening Stock	Initial stock quantity when adding the product.
Current Stock	Auto-updated on every sale and purchase. Shown in real time.
Minimum Stock Alert	Triggers low stock alert when current stock falls to this level.
Stock Auto-Update	Stock automatically decreases on sales, increases on purchases.

🧾 Module 5: Sales Invoice

Create professional GST-compliant tax invoices for your customers. The billing engine handles all GST calculations automatically.

Feature	Description
Auto Invoice Number	Sequential invoice numbers with your prefix (e.g., INV-0001).
Customer Search	Search and select customer — GSTIN and address auto-filled.
Invoice Date	Date of the invoice (defaults to today).
Due Date	Optional payment due date.
Supply Type	Intra-State (CGST + SGST) or Inter-State (IGST) — auto-selects GST type.
Product Search	Search products by name — price, HSN, GST rate auto-filled.
Quantity & Rate	Enter quantity and rate per unit.
Discount	Per-item discount in percentage.
Auto Tax Calculation	CGST, SGST, IGST automatically calculated based on supply type.
GST Rates	0%, 0.25%, 3%, 5%, 12%, 18%, 28% supported per item.
Multiple Items	Add unlimited line items to one invoice.
Round Off	Automatic round-off as per GST rules.
Notes	Payment terms, delivery notes, or any message on the invoice.
Edit Invoice	Edit any invoice — stock is automatically adjusted.
View Invoice	Detailed view with items, totals, and payment history.
Delete Invoice	Soft-delete an invoice.
Search & Filter	Search by invoice number or customer name.

How to Create an Invoice

Click Invoices in the left menu.
Click + New Invoice.
Search and select the customer from the Bill To field.
Set the Invoice Date and Due Date.
Select Supply Type — Intra-State or Inter-State.
In the Items section, search for a product. Price and GST rate will auto-fill.
Enter Quantity. Discount is optional.
Click + Add Item to add more products.
Review the Summary section for totals.
Click Save Invoice.

Invoice Actions

Feature	Description
View	Open invoice detail page with full breakdown and payment history.
Edit	Modify the invoice — all calculations update automatically.
Print	Generate a professional PDF and open it for printing.
WA (WhatsApp)	Send the invoice PDF directly via WhatsApp to the customer.
Email	Send the invoice PDF as an email attachment.
Delete	Soft-delete the invoice.

🛒 Module 6: Purchase Management

Record supplier purchases to track inventory inward, manage accounts payable, and claim Input Tax Credit (ITC).

Feature	Description
Auto Purchase Number	Sequential purchase numbers (e.g., PUR-0001).
Supplier Invoice No	Record the supplier's own invoice number for reference.
Supplier Search	Search and select supplier — GSTIN auto-filled.
Purchase Date	Date of purchase.
Supply Type	Intra-State or Inter-State for correct ITC calculation.
Product Search	Search products — purchase price, HSN, GST rate auto-filled.
Stock Auto-Update	Stock automatically increases on saving a purchase.
ITC Tracking	GST paid on purchases is tracked as Input Tax Credit.
Payment Status	Mark as Unpaid, Partial, or Paid.
Payment Mode	Cash, UPI, NEFT, RTGS, Cheque, Card.
Edit Purchase	Edit purchase — stock is adjusted automatically.
Delete Purchase	Delete purchase — stock is reversed automatically.

Purchase Payment Tracking

Record payments made to suppliers against purchase invoices.
Click View on any purchase to open the Purchase Detail page.
Click Record Payment to enter payment amount, date, mode, and reference.
Payment status (Unpaid / Partial / Paid) updates automatically.
Full payment history is shown on the Purchase Detail page.

💰 Module 7: Payment & Collections

Track all payments received from customers and manage outstanding dues.

Feature	Description
Payment History Tab	View all payments received — date, invoice, customer, amount, mode.
Pending Invoices Tab	List of all unpaid and partially paid invoices with balance due.
Record Payment	Record a payment against a specific invoice.
Payment Amount	Enter full or partial payment amount.
Payment Date	Date the payment was received.
Payment Mode	Cash, UPI, NEFT, RTGS, Cheque, Card, Other.
Reference / UTR	Transaction ID, cheque number, or UTR for bank transfers.
Notes	Optional notes about the payment.
Auto Status Update	Invoice status auto-updates to Paid, Partial, or Unpaid based on payments.
Delete Payment	Delete a payment — invoice status reverts automatically.
Search	Search payment history by invoice number, customer, or payment mode.

How to Record a Payment

Click Payments in the left menu.
Go to Pending Invoices tab to see all outstanding invoices.
Click Record Payment next to the invoice.
Enter the Amount, Date, Mode, and Reference.
Click Record Payment to save.
Alternatively, open any invoice (View) and click Record Payment from the Invoice Detail page.

💸 Module 8: Expense Tracking

Track all business operating expenses for accurate Profit & Loss calculation.

Feature	Description
Expense Categories	Pre-defined categories: Rent, Salary, Electricity, Internet, Transport, Marketing, Maintenance, Office Supplies, Bank Charges, Other.
Custom Categories	Add your own expense categories from the Categories tab.
Add Expense	Record an expense with date, category, description, amount, and payment mode.
Edit Expense	Modify any expense entry.
Delete Expense	Remove an expense entry.
Date Range Filter	Filter expenses by date range — This Month, This Year, or custom.
Category Summary	See total expense per category for the selected period.
P&L Integration	Expenses automatically deducted in Profit & Loss report for accurate net profit.
Payment Mode	Cash, UPI, NEFT, RTGS, Cheque, Card.
Reference	Bill number, transaction ID, or any reference for the expense.

🔧 Module 9: Stock Adjustment

Manually correct stock levels for damaged goods, physical count differences, theft, or any other reason.

Feature	Description
Add Stock	Increase stock quantity for a product.
Subtract Stock	Decrease stock quantity for a product.
Set Stock	Set stock to an exact quantity (physical count correction).
Reason Selection	Choose from: Physical count correction, Damaged goods, Expired goods, Theft / Loss, Opening stock entry, Return from customer, Sample / Demo, Other.
Preview	Shows new stock quantity before saving.
Adjustment History	Complete log of all stock adjustments with date, type, quantity, and reason.
Product List	View all products with current stock and minimum stock. Low stock items highlighted in red.

🖨️ Module 10: PDF Generation

Generate professional, GST-compliant invoice PDFs with your company details, logo, and bank information.

Feature	Description
Company Header	Company name, GSTIN, address, phone, email at the top.
Bill From / Bill To	Seller and buyer details clearly shown.
Item Table	All line items with HSN, quantity, rate, discount, taxable amount, GST breakup.
GST Breakup	CGST + SGST for intra-state, IGST for inter-state invoices.
Totals Section	Subtotal, taxable amount, CGST, SGST/IGST, total tax, round off, grand total.
Bank Details	Bank name, account number, IFSC, branch for payment reference.
Notes	Custom notes printed on the invoice.
Authorised Signatory	Signature block with company name.
Payment Status	Paid / Unpaid / Partial badge on the invoice.
Auto Open	PDF opens automatically after generation for printing.

💬 Module 11: WhatsApp Integration

Send invoices directly to customers via WhatsApp with the invoice PDF attached.

Feature	Description
QR Code Login	Scan the QR code with WhatsApp on your phone to connect.
Auto Phone Fetch	Customer's phone number is automatically filled from the customer database.
Custom Message	Edit the message before sending.
PDF Attachment	Invoice PDF is automatically generated and attached.
Connection Status	Shows Connected / Offline / Connecting status.
Disconnect	Logout from WhatsApp at any time.
7-day Grace	WhatsApp session stays connected across app restarts.

How to Send Invoice via WhatsApp

On the Invoices page, click WA next to the invoice.
If WhatsApp is not connected, click Connect and scan the QR code with your phone.
Once connected, the customer's phone number is auto-filled.
Edit the message if needed.
Click Send Invoice.

📧 Module 12: Email Integration

Send invoices to customers via email with the PDF automatically attached.

Email Setup

Before sending emails, configure your SMTP settings in Settings → Email Configuration.

Feature	Description
Sender Name	Name shown to the recipient.
Email Address	Your business email address.
App Password	For Gmail: generate an App Password (Settings → Security → 2-Step Verification → App Passwords).
SMTP Host	Pre-configured presets for Gmail, Outlook, Yahoo, Zoho.
Port	Default 587 for TLS. Use 465 for SSL.
Test Connection	Verify your SMTP settings before sending.

Email Features

Feature	Description
Auto Email Fetch	Customer's email is auto-filled from the database.
Custom Subject	Edit the email subject before sending.
Custom Message	Edit the email body.
PDF Attachment	Invoice PDF is automatically generated and attached.
HTML Email	Professional HTML email with your branding.
Multi-Provider	Works with Gmail, Outlook, Yahoo, Zoho, and any SMTP provider.

📈 Module 13: Reports

Comprehensive business reports with date range filters and PDF export for all report types.

1. Sales Report

Feature	Description
Period Filter	Filter by date range — This Month, Last Month, This Year, or custom.
Summary Cards	Total Sales, Total Tax, Amount Collected, Total Invoices.
Invoice List	All invoices for the period with taxable, tax, total, paid, balance, status.
Totals Row	Grand total at the bottom of the table.
Print PDF	Export the complete sales report as a formatted PDF.

2. Purchase Report

Feature	Description
Period Filter	Date range filter with quick presets.
Summary Cards	Total Purchases, Total ITC, Amount Paid, Total Invoices.
Supplier Wise Tab	Purchase breakdown by supplier — total, ITC, paid, balance.
Invoice List Tab	All purchase invoices for the period.
Print PDF	Export purchase report as PDF.

3. GST Report

Feature	Description
Summary Cards	Total Taxable Amount, CGST, SGST, IGST.
ITC Section	Input Tax Credit from purchases — CGST ITC, SGST ITC, IGST ITC.
GST Payable	Net GST payable after deducting ITC from collected GST.
HSN Summary Tab	HSN-wise taxable amount, CGST, SGST, IGST, total tax.
Invoice Wise Tab	Invoice-level GST detail with customer GSTIN.
Print PDF	Export GST report with full details.

4. Stock Report

Feature	Description
Summary Cards	Total Products, Low Stock Items, Stock Value (Sale), Stock Value (Purchase).
All Products Tab	Full product list with current stock, minimum stock, prices, stock value, status.
Low Stock Tab	Only products at or below minimum stock level.
Search	Search products by name or HSN code.
Print PDF	Export stock report as PDF.

5. Party Ledger

Feature	Description
Customer Selection	Select any customer from the left panel.
Customer Summary	Total business, amount paid, outstanding balance.
Invoice History	All invoices for the selected customer.
Payment History	All payments received from the selected customer.
Print PDF	Export party ledger with full details for the selected customer.

6. Outstanding Dues

Feature	Description
Customer List	All customers with pending dues.
Total Outstanding	Grand total of all pending amounts.
Collection Progress	Visual progress bar showing collection percentage per customer.
Search	Search by customer name.
Print PDF	Export outstanding dues report.

7. Profit & Loss Statement

Feature	Description
Income Section	Gross Revenue, Taxable Sales, GST Collected, Amount Collected.
COGS Section	Cost of Goods Sold from purchase data.
Expenses Section	Operating expenses by category (Rent, Salary, etc.).
Gross Profit	Revenue minus Cost of Goods Sold.
Net Profit	Gross Profit minus Operating Expenses.
Profit Margin	Net Profit as a percentage of Revenue.
Monthly Breakdown	Month-wise revenue and sales data for the period.
Print PDF	Export P&L statement as professional PDF.

📤 Module 14: GST Export (GSTR-1)

Export GSTR-1 JSON file for direct upload to the GST portal. The file is generated as per the official GST portal specifications.

Feature	Description
B2B	All invoices to GST-registered customers (with GSTIN).
B2CL	Inter-state invoices to unregistered customers above ₹2.5 lakh.
B2CS	Intra-state and small inter-state invoices to unregistered customers.
HSN Summary	HSN/SAC wise quantity, value, and tax summary.
Period Filter	Select date range for the export.
JSON Format	Standard JSON format accepted by the GST portal.
Save File	Choose where to save the exported JSON file.

How to Upload to GST Portal

Go to Settings → GST Export.
Select the date range (e.g., April 1 to June 30 for Q1).
Click Export GSTR-1 JSON.
Save the file to your computer.
Login to gst.gov.in.
Go to Services → Returns → Returns Dashboard.
Select the tax period and click GSTR-1.
Click Upload JSON and select the exported file.
Verify the data and submit.

⚙️ Module 15: Settings

Company Profile

Configure your business information that appears on all invoices and reports.

Feature	Description
Business Info	Company Name, GSTIN, PAN, Phone, Email, Website.
Address	Street address, City, State (with State Code auto-fill), Pincode.
Bank Details	Bank Name, Account Number, IFSC Code, Branch — printed on invoices.
Invoice Settings	Invoice Prefix (e.g., INV) and Financial Year.

Email Configuration

Setup SMTP to send invoices via email.

Feature	Description
Sender Name	Name shown to email recipients.
Email & Password	Your email and App Password (use App Password for Gmail).
SMTP Settings	Host, Port, SSL/TLS toggle. Quick presets for Gmail, Outlook, Yahoo, Zoho.
Test Connection	Verify your settings before sending invoices.

Tax Settings (HSN/SAC Codes)

Maintain a master list of HSN/SAC codes and their default tax rates.

Feature	Description
Add HSN Code	Add new HSN or SAC code with description and GST rate.
Edit / Delete	Modify or remove HSN codes.
Tax Rate Filter	View codes by GST rate (0%, 0.25%, 3%, 5%, 12%, 18%, 28%).
Search	Search by code or description.

Backup & Restore

Feature	Description
Create Backup	Save a copy of your database to any location on your computer or external drive.
Restore Backup	Replace current data with a backup file. Current data is auto-backed up before restore.
Auto Backup	Quick backup to the app data folder. Keeps last 7 daily backups automatically.

License

Feature	Description
License Status	Shows current license status — Active, Offline Mode, or Expired.
License Key	Displays your masked license key.
Licensed To	Name registered with the license.
Expiry Date	When your license expires. Warning shown 30 days before expiry.
Device ID	Your unique device ID — share with support for license transfer.
Renew License	Enter a new license key to renew or change your subscription.
Refresh Status	Re-verify license status with the server.

🔑 Licensing & Subscription

License Types

Simple Billing uses a hardware-based licensing system. Your license is tied to one computer.

Feature	Description
Online Verification	License is verified online each time you use the software.
Offline Grace Period	If internet is unavailable, the software works for 7 days from the last online check.
Device Lock	License is locked to one device. Contact support for device transfer.
Expiry Alert	30-day, 15-day, and 7-day warnings before license expiry.
Renewal	Renew from Settings → License by entering your new key.

Contact & Support

Feature	Description
Phone	+91 8902391021
Email	support@pspsoft.tech
Website	https://pspsoft.tech
Hours	Monday to Saturday, 10:00 AM to 6:00 PM IST

❓ Frequently Asked Questions (FAQ)

General

Q: Does Simple Billing work without internet?
Yes. Simple Billing works fully offline. Internet is only needed for initial license activation, license renewal, and sending invoices via WhatsApp/Email. The software will work offline for 7 days without re-verification.

Q: Where is my data stored?
All data is stored locally on your computer in a SQLite database file. The default location is: C:\Users\[YourName]\AppData\Roaming\Simple Billing\gst-billing.db

Q: Can I use Simple Billing on multiple computers?
One license works on one computer. For multiple computers, you need separate licenses. Contact PSP Softech for multi-seat pricing.

Invoicing

Q: Can I edit an invoice after saving?
Yes. Click Edit on any invoice to modify it. Stock levels are automatically adjusted when you edit or delete invoices.

Q: How do I handle GST for inter-state sales?
When creating an invoice, select Inter-State (IGST) in the Supply Type field. IGST will be calculated instead of CGST + SGST.

Q: Can I send invoices in bulk via WhatsApp?
Currently, invoices are sent one at a time. Bulk sending is planned for a future update.

GST & Tax

Q: How do I export GSTR-1?
Go to Settings → GST Export, select the tax period, and click Export GSTR-1 JSON. Upload this file on the GST portal at gst.gov.in.

Q: How is ITC calculated?
ITC is tracked from purchase invoices. In the GST Report, you will see Total ITC (from purchases) deducted from GST Collected (from sales) to show Net GST Payable.

Technical

Q: How do I take a backup?
Go to Settings → Backup & Restore → Create Backup. Save the .db file to your preferred location. It is recommended to backup to an external drive or cloud storage.

Q: My license expired. What do I do?
Contact PSP Softech to purchase a renewal. Once you receive your new license key, go to Settings → License, enter the new key, and click Activate License.