How is VAT handled?

Everything down to the tax line is VAT inclusive, the way you read your own shop. Net Revenue and every line below it is VAT exclusive.

The tax line is the VAT contained in what you actually kept: Shopify's tax lines minus refunded tax. This split is what makes margins honest, because a percentage computed on VAT-inclusive revenue is flattered by the whole VAT rate, and every cost share below the tax line is measured against money that is actually yours.