Fees

Boros charges various fees to maintain protocol sustainability. This section outlines all fee types that users should be aware of when trading on the platform.

Position Opening Fees

Boros charges fees when opening new positions through:

• Taker orders: When executing against existing orders in the order book
• OTC swaps: When opening direct swaps with other users (typically AMMs)

Important: Maker orders (limit orders placed in the order book) incur no fees when placed. Fees are only charged to the taker when these orders are filled.

Fee Formula

Both taker orders and OTC swaps follow the same fee calculation:

Fee = |Position Size| × Fee Rate × Time to Maturity

Where:

• Position Size: The notional size of the position being opened
• Fee Rate: Configured per market — takerFee for order book trades and otcFee for OTC swaps (e.g., AMM interactions). Typical value: 0.05% (0.0005). Query the exact rates via getMarketConfig() or getBestFeeRates()
• Time to Maturity: The time remaining until the swap maturity, expressed in years

Fee Discounts: Some accounts may have personal discount rates (takerDisc, otcDisc) that reduce the effective fee. The getBestFeeRates() function returns the actual rate after applying any applicable discounts.

Example

Suppose you want to open a long position by taking an order:

• Position size: 100 ETH
• Current time: January 1, 2025
• Maturity: April 1, 2025 (90 days = 0.2466 years)
• Fee rate: 0.05%

Fee = 100 ETH × 0.0005 × 0.2466 = 0.01233 ETH

The same fee calculation applies for OTC swaps of the same size and maturity.

Settlement Fees

Boros charges settlement fees on all open positions during each periodic payment settlement.

Fee Formula

Settlement fees are calculated as:

Settlement Fee = |Position Size| × Settlement Fee Rate × Settlement Period

Where:

• Position Size: The absolute value of your current position size
• Settlement Fee Rate: Set by the protocol (varies by market)
• Settlement Period: Typically 8 hours (8/8760 = 0.000913 years)

Example

For an open position during settlement:

• Position size: 50 ETH (long)
• Settlement fee rate: 0.2% (0.002)
• Settlement period: 8 hours = 0.000913 years

Settlement Fee = 50 ETH × 0.002 × 0.000913 = 0.0000913 ETH

This fee is charged every 8 hours (or the configured settlement period) for as long as the position remains open.

Market Entrance Fees

A one-time market entrance fee is charged when you perform your first action in any specific market.

The entrance fee is denominated in the base asset of the market:

• BTC markets: 0.000008 BTC (approx. $1 USD)
• ETH markets: 0.00027 ETH (approx. $1 USD)

You can check if you've already paid the entrance fee by calling:

bool hasEntered = MarketHub.hasEnteredMarketBefore(userAccount, marketId);

If hasEntered returns true, you won't be charged the entrance fee again for that market.

Liquidation Fees

When an account is liquidated, a fee is charged on the liquidated position and collected by the protocol treasury. This fee is separate from the liquidation incentive paid to the liquidator.

Liquidation Fee = |Liquidated Size| × LiqSettings.feeRate × Time to Maturity

The feeRate is part of the market's LiqSettings configuration. It follows the same time-scaling pattern as position opening fees.

Fee Summary

Fee Type	When Charged	Rate Source	Discountable
Taker fee	Order fills against book	MarketConfig.takerFee	Yes (takerDisc)
OTC fee	AMM swaps / OTC trades	MarketConfig.otcFee	Yes (otcDisc)
Settlement fee	Each funding period	FIndex.feeIndex	No
Market entrance fee	First action per market	CashFeeData.marketEntranceFee	No
Liquidation fee	Account liquidated	LiqSettings.feeRate	No