No it is not possible. The invoice number comes from the "Source Document" provided to the company by the vendor the company purchased the goods and or services from. This is part of the rules from CRA when posting (creating) invoices from vendors. Technically it follows the Objectivity Principle. 

Ok, worth a try, thanks.

Dave

Not entirely sure I made my intention clear. For example - I have a number of invoices from Tim Horton's, paid for in cash. They are not numbered by the supplier. I want to post each of them and provide some sort of audit trail. Having Sage provide a transaction number would do that for me.

Dave

Dave, I just looked at my Timmies receipt from this morning and it has an 8 digit Receipt number just above the HST number, though mine was paid by credit card.

Some providers do have a number, others don't. I just used Tim as an example. I'm switching from Quickbooks to Sage. QB would do it no problem.

Dave123 said:

Having Sage provide a transaction number would do that for me

There is an option in Setup | User Preferences | Transaction Confirmation for:

[ ] Tell me when a transaction is posted or recorded successfully

That will display the journal entry number, which is unique for that financial year.  We write or stamp that on the source document as a cross-reference for audit.

For CC payments where there is no other reference visible we use the 6 digit Approval Code as an invoice number.  (it may not be unique but we never have a collision).  I don't think it's reasonable to type in ref # 'C84097625-001-001-651-0' for a car wash receipt.

Dave123 said:

Some providers do have a number, others don't

Even old cash register receipts usually have have a non-repeating serial number.  For CC expense payments without a receipt turned in, I use the ISO date followed by the person's initials and the type of card. 

Thanks, that should work.

Dave