I've received an invoice from a company. I am going to pay it, but would appreciate some advice on when it is due. The invoice states a tax point date and an invoice date, but no invoice due date. I plan to pay at the end of the first week in Oct, when I get paid. The company state that because they have titled the invoice a "demand invoice" it is payable immediately. I think that a demand notice and an invoice are two separate things, and calling an invoice a "demand" invoice doesn't mean it has to be paid immediately. Who is correct here?