First: this is not tax advice
Tax and invoicing rules for household businesses are changing, with some milestones from 2026 (to be verified). Every business is different. Before deciding anything, ask your tax office or an accountant.
Worth doing whatever the rules say
Record every sale: what, how much, and how the customer paid. Keep cash and transfers clearly apart. Keep a steady history by day and by month.
With tidy books now, when you need to issue invoices or declare, the figures are already there.
Who issues e-invoices
E-invoices are issued through licensed e-invoice providers (check the exact conditions with the tax authority). Sales software usually connects to such a provider to pass order data along, so nothing is typed twice.
Where Hensa stands
Hensa doesn’t issue e-invoices yet; it’s planned, through licensed providers. What you can do today is make every payment match an order: that is the data an invoice will need later.