Fees

EthAnchor is built using various blockchain infrastructure, which charges fees on their usage. Using EthAnchor incurs fees that are calculated based on the deposit / redeem amount. Fees listed at this section are applied independent of gas spent on Ethereum transactions.

Operation	# of Shuttle Fee	# of Terra Tax
deposit_stable	Once	Once
redeem_stable	Once	Twice

Shuttle Fee

Shuttle ignores transfer requests with a transfer value smaller than 1 UST.

Cross-chain transfers of Terra stablecoins and aTerra tokens between Ethereum and Terra are facilitated with the use of Shuttle. Shuttle charges a fee only for cross-chain token transfers from Terra to Ethereum, with the fee amount being:

$$\text{shuttleFee}=\text{max} (1\,\text{UST},\,\text{transferAmount} \cdot 0.1\% )$$

0.1% of the transfer amount is charged as Shuttle fees, decreasing with the transfer amount until the fee reaches the 1 UST minimum. Amount received after fees will be:

$$\text{receiveAmount} = (1-\text{shuttleFee}) \cdot \text{transferAmount}$$

Note that this fee will be applied once for both deposit_stable and redeem_stable.

Terra Blockchain Tax

Terra stablecoin transfers that occur on the Terra blockchain are require a Terra tax (protocol fee) to be paid. Tax amount is dependent on the transfer amount, represented as:

$$\text{terraTax} = \text{min}(\text{taxCap}, \text{transferAmount}\cdot\text{taxRate})$$

Tax amount increases with as transfer amount increases, until it reaches a cap of 1 TerraSDR (SDT), currently valued at around ~1.42 UST. Terra SDR is a Terra stablecoin pegged to the International Monetary Fund's Special Drawing Rights (SDR) and its value -- along with the tax cap -- may differ as exchange rates vary with time.

EthAnchor is configured to automatically deduct the amount of stablecoins required for tax before making Terra-side transfers. Thus the post-transfer receive amount will be:

$$\text{receiveAmount} = \frac{1}{1+\text{terraTax}}\cdot\text{transferAmount}$$

Note that this tax fee is applied once for deposit_stable and twice for redeem_stable.