This extension enhances your invoice system in two powerful ways:

First, it makes your invoice prefix dynamic by allowing it to adapt automatically to the current date (day, month, and/or year) using a flexible custom format. That means no more manually updating the invoice prefix every time the date changes.

Second, it ensures your invoice numbers have a fixed length by padding them with leading zeros. Whether it’s invoice #1 or #10,000, all numbers will appear uniform and professional.

Requirements

• For OpenCart 4, this extension requires VQMod.
• Please ensure VQMod version 2.6.7 or newer is installed.

How It Works

I. Use Dynamic Tags in Your Invoice Prefix

You can now use dynamic tags within square brackets [ ] when setting your invoice prefix. These tags represent elements of the date (and even time, if needed).

Supported Tags:

• d - Day of the month (01–31)
• D - Short day name (e.g., Mon, Tue)
• j - Day of the month without leading zero (1–31)
• l - Full day name (e.g., Monday)
• N - ISO day number (1 = Monday)
• w - Day number (0 = Sunday)
• z - Day of the year (0–365)
• W - ISO week number
• F - Full month name (e.g., April)
• m - Month (01–12)
• M - Short month name (e.g., Apr)
• n - Month without leading zero (1–12)
• t - Days in current month
• L - Leap year? (1 = yes, 0 = no)
• o - ISO year
• Y - Full year (e.g., 2025)
• y - Year (2 digits, e.g., 25)

Example:

If your invoice prefix is: INV/DIY/[y]/[d]/
And today is April 17, 2017 — the result will be: INV/DIY/17/04/
(See Figure 1)

Note: In the default OpenCart system, invoice numbers reset to 1 for each unique prefix. This behavior allows you to auto-reset invoice numbers per day, month, or year—useful if you want to track invoices by date.

The tag system is based on the PHP date() function, so you can even include time-based tags (though not usually necessary). For example, G = hour in 24-hour format (0–23), which would reset invoice numbers every hour.

II. Set Fixed Digits for Invoice Numbers

The system will automatically pad invoice numbers with leading zeros, ensuring they all have the same number of digits regardless of value.

Example:

If you set the digit count to 6, your invoice numbers will look like:

• INV-2017-000001
• INV-2017-000534
• INV-2017-079642

Note: If the actual invoice number already meets or exceeds the configured digit count, the format will remain unchanged.

Demo — Try Before You Buy

Want to explore how it works? Try it on our admin demo page.

Username: demo
Password: aauwwo

Navigate to: System > Settings > Edit Store > Option Tab

To test the invoice behavior:

1. Visit the frontend demo site.
2. Place a new order.
3. Return to the admin demo panel.
4. Go to: Sales > Orders > Edit
5. Generate the invoice.
6. Review the generated invoice and see the result for yourself.