If you are using any accounting software or accounting firm services, then it is best to contact them. Most programs should be already fully customized. If the accounting software is unable to do so, you should develop the appropriate feature or switch to more modern software.
If you only need to send small quantities of e-invoices, then the e-invoice can be sent free of charge via the government-generated e-invoice information system. The software is located in the Company Portal of the E-Business Registry and can be used by companies as well as accountants, financial managers and other authorized company representatives. All companies and organizations involved in electronic invoicing can send e-invoices to the public sector free of charge, in unlimited quantities and for an indefinite period.
When the quantity of your invoices is already bigger, it is wise to choose an e-invoice operator in order to significantly improve the efficiency of your billing activities with various smart solutions. Then you have to make an agreement with a company that offers e-invoicing services (e.g. Omniva, Tieto Estonia, Envoice).