Is all service being sold with VAT in Finland from a Finnish company to a Finnish company?
Essential in VAT is to understand what is the place of sale of the service. When selling to business operators, the place of sale of the service is Finland if the service has been delivered to a fixed establishment in Finland. If the service has not been delivered to a fixed establishment, the service is being sold in Finland if the domicile of the buyer is in Finland. This is the general rule in selling services.
If the seller is not liable for VAT in Finland and does not have fixed establishment in Finland, reverse charge is applied. This means that liable for VAT is the buyer , not the seller as usual. To prove that your transaction is intracommunity trade you need buyer's VAT id.
A Finnish company A sells consulting service to a Finnish company B. Place of sale of service is Finland. Liable for VAT is the seller. The seller sends an invoice with Finnish VAT. Most services are sold with VAT.