Why does my quickbooks generated invoice number now have a letter at the end of it and it is not the following number of my last created invoice?

Hi there,

Welcome to the Community. QuickBooks allows you to enter a custom invoice number and I'll be happy to show you how. 

QuickBooks automatically assigns numbers to your sales forms starting with 1001. If you would rather use your own numbering format, you can customize the number to whatever you prefer.

Here's how:

Set your own numbering preference

Use the Custom transaction numbers feature to set your own numbering preference. This adds an Invoice no. field where you can enter any number or letter format you want.

1. Select the Gear icon on the Toolbar, then Account and Settings (or Company Settings).
2. Select Sales, then select anywhere within the Sales form content section.
3. Check the box next to Custom transaction numbers.
4. Select Save and then Done.
5. Open an invoice or any sales form, and in the Invoice no. field, enter the custom number or letter sequence you want to use for your forms. The sequence you set here applies to all sales forms.

Knowing this, you can now change the invoice number and re-use it for the same customer. If you're looking to keep the invoice details but change the customer, QBO won't allow that. The program will remove any linked transactions if the invoice is now for a different customer. 

In case you have other questions, feel free to contact our support team using this link here.