Rule reminder
Causal conjunctions operate across a register spectrum: INFORMAL: perché, visto che, dato che. NEUTRAL-FORMAL: siccome, visto che, dal momento che, dato che. FORMAL: poiché, in quanto. VERY FORMAL/LITERARY: giacché, poiché, participio assoluto, causal gerund. The same cause can be expressed at different registers. Choosing the right register is essential in professional and academic Italian.
In a business email to a client, which is best for 'since we did not receive payment'?