When either generating cash sale invoices or running a credit invoicing batch, there is a ledger (company) setting to determine which date is used as the invoice date.
Tax Point Date
If a VAT invoice has been issued within 14 days of the supply, the tax point will be the date of the invoice.
If a VAT invoice has been issued 15 days or more after the date of supply, the tax point will be the date of supply.
When the invoice is generated the current date will be set as the date of invoice
Whenever the invoice is generated the #supplydate (date of delivery or collection) will be set as the date of invoice.
Setting the Invoice Date criteria
In Settings > Organisation Settings > Financial Ledger Settings
Double click on the relevant Ledger
Select the 'Invoicing' tab
Select the desired option from the drop down 'Invoice date basis'
NOTE: This will apply to future generated invoices, but will not adjust the invoice date on existing invoices.