Trilogy in Solana: Transfer Fee, Interest-Bearing, and Nontransferable

Token-2022 is the upgraded SPL token program on Solana, bringing native extensions that allow a single mint to opt into advanced behaviors without custom programs. This week, I explored three powerful extensions: Transfer Fees, Interest-Bearing tokens, and Non-Transferable tokens. Think of these extensions as middleware for your tokens—enforced at the protocol level.

The Transfer Fee Mint

Mint Address: FeoMWHjNJgJM6iEQUnUjsJsdPtP3Cu9m99iiuz9RhALG

I configured this token to skim a fee on every transfer. This is perfect for protocol treasuries or community currencies where a small percentage of every transaction supports the ecosystem.

spl-token create-token --program-id TokenzQdBNbLqP5VEhdkThT93YfkdY59uL35t4Z5Xl --transfer-fee 100 5000

This command sets a 1% fee (100 basis points) with a maximum cap of 5000 lamports.

The Interest-Bearing Mint

Mint Address: 6vZ9eXTTtGCpwRVLGg6uuyLXxk2yYEykroBTNybf6wT3

This extension allows a token to accrue interest over time. Crucially, it doesn't mint new supply; instead, the UI-displayed amount updates based on the on-chain rate.

spl-token create-token --program-id TokenzQdBNbLqP5VEhdkThT93YfkdY59uL35t4Z5Xl --interest-rate 10

NB: Remember that the rate is stored on-chain, but the principal balance remains the same until updated. It's a clever way to handle yield display natively.

The Non-Transferable Mint

Mint Address: 3PWCwuiPauNhYxwArDGaRizKLpJHETLS7RNRqHL1AQvm

Finally, I built a "Soul-bound" token. Once minted to an account, it cannot be transferred or moved. I tested this by attempting a transfer and received a satisfyingly firm error: Program log: Transfer is disabled for this mint: custom program error: 0x25.

spl-token create-token --program-id TokenzQdBNbLqP5VEhdkThT93YfkdY59uL35t4Z5Xl --enable-non-transferable

Take Home

What caught my attention this week is how simple it is to compose these behaviors. Native extensions remove the need for "wrapped" versions of tokens to get simple features like fees or interest. I’m excited to see how these primitives will be used in real products for loyalty programs.