What happens if you cast a spell and your opponent counters it — do you still pay the cost?

When you cast a spell, the process follows a strict sequence defined in CR 601.2. You announce the spell, make all choices, and then pay all costs (mana, life, sacrificed permanents, etc.). Only after costs are fully paid does the spell become a spell on the stack waiting to resolve.

After costs are paid, players receive priority and may respond — this is when your opponent can cast a counterspell (CR 116.3). If the counterspell resolves, your spell is countered and moved to the graveyard (CR 701.5a). The game does not reverse the cost payment; mana already spent is gone, and anything else you paid (like a sacrificed permanent) stays gone.

Think of it like paying for a meal at a restaurant — if the kitchen burns it, you don't automatically get a refund. The transaction (cost payment) and the delivery (spell resolution) are two separate events.

Concrete example: You cast Lightning Bolt, paying {R}. Your opponent responds with Counterspell. The {R} mana you spent is already gone from your mana pool. When Counterspell resolves, Lightning Bolt is put into your graveyard countered — and you do not get your {R} back.

The only exception worth noting is if a card specifically says costs are refunded (e.g., some cards with the Buyback or similar mechanics have specific text, but those are self-contained rules on those cards, not a general principle). By default, countering a spell never refunds its costs (CR 601.2h, 701.5).