If you need the invoice for a ticket bought through Iberia.com or Serviberia for a company in Spain,* Gibraltar or Andorra, you can request it through Request invoice.
If you also need the invoice for advance seat selection, you can manage it separately on the same page.
If you want an invoice for a ticket bought through any other channel, please contact them directly.
* VAT on air tickets is regulated by Law 37/1992 of 28 December on Value Added Tax. The VAT rate for domestic flights is 10%. International flights and flights with a destination or origin in the Canary Islands are exempt. Flights to the Balearic Islands are also subject to 10% VAT. However, the rate for the part over international waters is exempt.