VAT number (or TRN number in UAE) is important to be printed in receipts, invoices and bills. as tax authority departments will fines you if there is no tax number on header of your prints.
You can put your Tax number (TRN number) in iGreen accounting software in on click only. please watch below video to see how to do it.
Note: Tax percent in UAE is 5% but in other countries maybe is different. please pat attention to this matter.