Invoice Calculations Verification

Road Project Bill Verification

Project Cost (₹)

Allocation (%)

Negotiation (%)

GST Rate (%)

Project Name

Bill No.

Cumulative Prev. Paid

Budget Limit (₹)

Item Description	Contract (₹)	This Month (₹)	Remaining Balance
1. Sub-Total Amount (Gross)		0.00	-
2. Negotiation Amount (4.59%) [Deduction]		- 0.00	-
3. Final Total Amount (Excl. GST)		0.00	-
4. GST Amount (18%) on Final Total		+ 0.00	-
NET PAYABLE AMOUNT (FOR BILL NO. 1)		₹ 0.00	-

⚠️ BUDGET EXCEEDED: Sum of all bills exceeds the allotted project funds!

Project History & Edit Options

Date	Project	Bill No	Amount	Actions

Road Project Bill Verification System – Technical Explanation

This application is designed for verification, tracking, and management of road project bills. It ensures financial control by calculating payable amounts, monitoring budget limits, and maintaining a complete history of billing records using a structured digital workflow.

1. Objective of the System

• Verify contractor bills against project budget
• Apply negotiation deductions and GST calculations
• Track cumulative payments
• Prevent budget overruns
• Maintain digital record of all bills

2. Input Parameters

• Project Cost: Total sanctioned project value
• Allocation %: Portion of budget allocated
• Negotiation %: Agreed deduction percentage
• GST %: Applicable tax rate
• Project Name: Identifier for tracking
• Bill No: Auto-generated sequence

3. Bill Item Structure

The system includes predefined cost heads:

• Professional Staff
• Supporting Staff
• Transportation
• Office Expenses
• Training & Contingencies

Each item includes:

• Contract Value
• Current Bill Amount
• Remaining Balance

4. Financial Calculation Logic

4.1 Sub-Total (Gross Amount)

SubTotal = Σ(Current Bill Amounts)

4.2 Negotiation Deduction

Negotiation Amount = SubTotal × (Negotiation %)

4.3 Final Amount (Excluding GST)

Final Amount = SubTotal - Negotiation Amount

4.4 GST Calculation

GST Amount = Final Amount × (GST %)

4.5 Net Payable Amount

Net Payable = Final Amount + GST

This represents the total amount payable for the current bill.

5. Budget Control Mechanism

5.1 Budget Limit

Budget Limit = Project Cost × Allocation %

5.2 Total Liability Check

Total Liability = Previous Paid + Current Bill Amount

If:

Total Liability > Budget Limit → Warning Triggered

System disables saving when budget is exceeded.

6. Data Storage (IndexedDB)

All billing records are stored in browser database:

indexedDB → "PWD_Final_Bills"

Each record contains:

• Project name
• Bill number
• Net payable amount
• Item-wise data
• Configuration (GST, negotiation, etc.)
• Timestamp

7. History & Editing System

The system maintains a full history of bills:

• Auto-increment bill numbers
• View previous records
• Edit/load existing entries
• Delete unwanted records

store.getAll() → Filter by project → Render table

8. Import / Export Feature

8.1 Export

Data can be downloaded as JSON:

JSON.stringify(records)

8.2 Import

Backup files can be restored into the system:

• File is read using FileReader
• Records inserted into IndexedDB
• IDs regenerated automatically

9. Workflow Summary

1. User enters project and bill details
2. Inputs current bill amounts
3. System calculates totals and deductions
4. Budget validation is performed
5. Bill is saved if within limit
6. History is updated automatically

10. Engineering & Administrative Benefits

• Prevents financial mismanagement
• Ensures transparency in billing
• Reduces manual calculation errors
• Provides quick audit trail

11. Assumptions

• All costs are inclusive of contract conditions
• Negotiation applies uniformly across items
• GST is applied on final amount only
• No escalation or variation considered

12. Limitations

• No multi-user synchronization
• No backend database (client-side only)
• No approval workflow
• No integration with accounting systems

13. Conclusion

This system acts as a digital bill verification and control tool for infrastructure projects. It combines financial accuracy with ease of use, making it highly suitable for engineers, auditors, and project managers.

For advanced deployment, the system can be extended with cloud databases, user authentication, and integration with ERP systems.