Tax authorities differ from country to country, but in NL, barter with a business has to be accompanied with an invoice, which is a document with a legal status. The way you pay, doesn't matter, but has to be of equal value expressed in EUR.

VAT depends on trade value (invoice), type of product or service, sector of the economy and purchaser.

BTC are regarded here as tokens in LETS (Local Exchange Trade Systems) and their fiscal value is the purchase value, whether by fiat or barter.

So you have anything exchanged of EUR value for BTC which you exchanged for EUR value. So you have a realised profit-loss in/out of BTC, since they have a different purchase and final exchange value, and the cost stated on the invoice of Bitfurystrikesback.com.

So the value you spent on the BTC you spend on f.e. a € 1.000 miner, is your net business cost for the miner (excl. time spent on your EUR<->BTC administration)