Fees
The pool's shield and exit fees, the relayer fee on sends and unshields, the network fee of a shield, and where the pool's fees go.
Voidcash has two pool fees, one on the way in and one on the way out, and none on private sends. Sends and unshields also pay the relayer that submits them. Every rate is read live from the pool program, and the app shows each fee in SOL before you confirm.
| Move | Pool fee at launch | Relayer fee | Network fee |
|---|---|---|---|
| Shield | None (shield fee 0%), charged on top when set | None | Paid by your wallet |
| Send | None, by design | Yes, from your notes | Paid by the relayer, inside its fee |
| Unshield | 0.5% of the amount (exit fee), taken from it | Yes, from your notes | Paid by the relayer, inside its fee |
| Combining notes | None | Yes, one per merge | Paid by the relayer, inside its fee |
Pool fees
| Parameter | At launch | Applies to | How it is charged |
|---|---|---|---|
| Shield fee | 0% | Every shield | On top: the note holds the amount you shield, and your wallet pays the fee besides |
| Exit fee | 0.5% | Every unshield | From the amount: the recipient receives the amount less the fee |
Both fees are a percentage of the amount, rounded down to the lamport. At 0.5%, unshielding 1 SOL costs 0.005 SOL in exit fee.
Private sends have no pool fee, by design. The program cannot see a send's amount, and it charges a zero rate to every transaction that moves no SOL in or out of the pool. Combining notes is a send to yourself, so it pays no pool fee either.
Who sets them
The shield fee and the exit fee are parameters of the pool, which the pool's admin can change. The program refuses either one above 1%; a higher fee would take a new version of the program. The rate in force is in the pool's config account, and the app reads it at every sync.
The rate the app shows you is bound in the proof. If the admin changes a fee after you confirm, the program refuses the transaction instead of charging the new rate: no pool fee is charged and no note is spent. The app picks up the new rate at its next sync, and the next review shows it.
Relayer fee
Sends, unshields and merges are submitted by a relayer, which pays the Solana fees and is paid back in SOL from your notes. Its fee is a quote, computed by the relayer as:
relayer fee = rent of two nullifier accounts
+ the transaction's network fee (base fee and priority fee)
+ a margin- Nullifier accounts. Every transaction creates two small accounts that mark the notes it spends as spent. They stay on the chain for good, so their rent is never returned.
- Network fee. The Solana base fee plus a priority fee for the compute the transaction reserves.
- Margin. A fixed amount the relayer adds to every quote.
The app reads the quote from the relayer when you unlock the vault, and the review shows it in SOL. The landing page shows the current quote too. The quote does not depend on the amount you move.
The fee is bound in the proof together with the relayer's address, so the relayer cannot raise it after you confirm. It refuses a request that pays less than its current quote, and it simulates every transaction before sending it: a request it refuses costs you nothing.
Network fee of a shield
A shield is a normal transaction from your wallet, so your wallet pays the Solana fee and the rent of the two nullifier accounts it creates. That is why the app keeps 0.01 SOL in the wallet when you press Max.
Where the pool fees go
Every pool fee is split in the same transaction that collects it:
| Share | At launch | Goes to |
|---|---|---|
| Buyback | 50% of each fee | The buyback account, which buys $VOID and burns it |
| Treasury | The rest, 50% | The treasury account, which the pool's admin can withdraw |
At launch the shield fee is zero, so the buyback receives 0.25% of every unshield and the treasury the other 0.25%. Rounding goes to the treasury, by at most a lamport. The buyback's share is also a parameter of the pool, from 0% to 100% of each fee.
The buyback
The buyback spends its SOL over time, in chunks, on the $VOID/SOL pool on Meteora (DAMM v2) that the admin pins it to, and burns every $VOID it buys in the same instruction. Anyone can trigger a buy, and the program pays the caller nothing; the relayer runs a crank that does it. The landing page shows the SOL waiting to buy $VOID and the total $VOID burned, both read from the program.
Relayer fees are not pool fees: they go to the relayer, for the costs above.