Interest bearing tokens

Configure the InterestBearingConfig extension to display UI-adjusted balances that accrue interest over time using Light Token.

Key Parameters

A configurable interest rate on the mint lets clients display a UI-adjusted balance that grows over time, while the on-chain token balance remains unchanged.

InterestBearingConfig is configured with these parameters:

Parameter	Description
rateAuthority	Account authorized to update the interest rate after initialization.
currentRate	Active interest rate in basis points (e.g., 500 = 5%).
initializationTimestamp	Network timestamp recorded when the extension is created.
lastUpdateTimestamp	Network timestamp of the most recent rate change, used as the reference for interest calculations.
preUpdateAverageRate	Previous rate value preserved when the rate authority updates currentRate.

This extension is fully supported by Light Token without restrictions.

Use InterestBearingConfig With Light Token

Agent skill

Install the agent skill:

npx skills add https://zkcompression.com

See the AI tools guide for dedicated skills.

Guide

Setup

npm install @lightprotocol/compressed-token@beta \
            @lightprotocol/stateless.js@beta \
            @solana/spl-token

Snippets below assume rpc, payer, mint, owner, recipient, and amount are defined. See the full examples for runnable setup.

import { createRpc } from "@lightprotocol/stateless.js";

const rpc = createRpc(RPC_ENDPOINT);

Create a Token-2022 Mint With Interest Bearing Config

Instruction

import {
    Keypair,
    SystemProgram,
    Transaction,
    sendAndConfirmTransaction,
} from "@solana/web3.js";
import { createRpc } from "@lightprotocol/stateless.js";
import { LightTokenProgram } from "@lightprotocol/compressed-token";
import {
    TOKEN_2022_PROGRAM_ID,
    getMintLen,
    createInitializeMint2Instruction,
    ExtensionType,
    createInitializeInterestBearingMintInstruction,
} from "@solana/spl-token";

const rpc = createRpc(RPC_ENDPOINT);

const mintKeypair = Keypair.generate();
const decimals = 9;
const rate = 500; // 5% interest rate in basis points

// Calculate space for mint + InterestBearingConfig extension
const mintLen = getMintLen([ExtensionType.InterestBearingConfig]);
const rentExemptBalance =
    await rpc.getMinimumBalanceForRentExemption(mintLen);

// Create account
const createAccountIx = SystemProgram.createAccount({
    fromPubkey: payer.publicKey,
    lamports: rentExemptBalance,
    newAccountPubkey: mintKeypair.publicKey,
    programId: TOKEN_2022_PROGRAM_ID,
    space: mintLen,
});

// Initialize InterestBearingConfig
const initInterestBearingIx =
    createInitializeInterestBearingMintInstruction(
        mintKeypair.publicKey,
        payer.publicKey, // rate authority
        rate,
        TOKEN_2022_PROGRAM_ID
    );

// Initialize mint
const initMintIx = createInitializeMint2Instruction(
    mintKeypair.publicKey,
    decimals,
    payer.publicKey,
    null,
    TOKEN_2022_PROGRAM_ID
);

// Register interface PDA with Light Token
const createSplInterfaceIx = await LightTokenProgram.createSplInterface({
    feePayer: payer.publicKey,
    mint: mintKeypair.publicKey,
    tokenProgramId: TOKEN_2022_PROGRAM_ID,
});

const tx = new Transaction().add(
    createAccountIx,
    initInterestBearingIx,
    initMintIx,
    createSplInterfaceIx
);

const signature = await sendAndConfirmTransaction(rpc, tx, [
    payer,
    mintKeypair,
]);

Action

import "dotenv/config";
import {
    Keypair,
    SystemProgram,
    Transaction,
    sendAndConfirmTransaction,
} from "@solana/web3.js";
import { createRpc } from "@lightprotocol/stateless.js";
import { LightTokenProgram } from "@lightprotocol/compressed-token";
import {
    TOKEN_2022_PROGRAM_ID,
    getMintLen,
    createInitializeMint2Instruction,
    ExtensionType,
    createInitializeInterestBearingMintInstruction,
} from "@solana/spl-token";
import { homedir } from "os";
import { readFileSync } from "fs";

// devnet:
// const RPC_URL = `https://devnet.helius-rpc.com?api-key=${process.env.API_KEY!}`;
// const rpc = createRpc(RPC_URL);
// localnet:
const rpc = createRpc();

const payer = Keypair.fromSecretKey(
    new Uint8Array(
        JSON.parse(readFileSync(`${homedir()}/.config/solana/id.json`, "utf8"))
    )
);

(async function () {
    const mintKeypair = Keypair.generate();
    const decimals = 9;
    const rate = 500; // 5% interest rate in basis points

    // Calculate space for mint + InterestBearingConfig extension
    const mintLen = getMintLen([ExtensionType.InterestBearingConfig]);
    const rentExemptBalance =
        await rpc.getMinimumBalanceForRentExemption(mintLen);

    // Instruction 1: Create account
    const createAccountIx = SystemProgram.createAccount({
        fromPubkey: payer.publicKey,
        lamports: rentExemptBalance,
        newAccountPubkey: mintKeypair.publicKey,
        programId: TOKEN_2022_PROGRAM_ID,
        space: mintLen,
    });

    // Instruction 2: Initialize InterestBearingConfig
    const initInterestBearingIx =
        createInitializeInterestBearingMintInstruction(
            mintKeypair.publicKey,
            payer.publicKey, // rate authority
            rate,
            TOKEN_2022_PROGRAM_ID
        );

    // Instruction 3: Initialize mint
    const initMintIx = createInitializeMint2Instruction(
        mintKeypair.publicKey,
        decimals,
        payer.publicKey, // mint authority
        null, // freeze authority
        TOKEN_2022_PROGRAM_ID
    );

    // Instruction 4: Create SPL interface PDA
    // Holds Token-2022 tokens when wrapped to light-token
    const createSplInterfaceIx = await LightTokenProgram.createSplInterface({
        feePayer: payer.publicKey,
        mint: mintKeypair.publicKey,
        tokenProgramId: TOKEN_2022_PROGRAM_ID,
    });

    const tx = new Transaction().add(
        createAccountIx,
        initInterestBearingIx,
        initMintIx,
        createSplInterfaceIx
    );

    const signature = await sendAndConfirmTransaction(rpc, tx, [
        payer,
        mintKeypair,
    ]);

    console.log("Mint:", mintKeypair.publicKey.toBase58());
    console.log("Tx:", signature);
})();

createMintInterface creates a basic Token 2022 mint with an interface PDA. To include the InterestBearingConfig extension, use the instruction approach shown in the other tab.

Create Interface PDA for Existing Mint

If you already have a Token-2022 mint with InterestBearingConfig, create an interface PDA with Light Token.

import { LightTokenProgram } from "@lightprotocol/compressed-token";
import { TOKEN_2022_PROGRAM_ID } from "@solana/spl-token";

const createSplInterfaceIx = await LightTokenProgram.createSplInterface({
    feePayer: payer.publicKey,
    mint: mintKeypair.publicKey,
    tokenProgramId: TOKEN_2022_PROGRAM_ID,
});

AI Prompt

Create a Token-2022 mint with InterestBearingConfig and register with Light Token

CopiedCopy promptOpen in Cursor

---
description: Create a Token-2022 mint with InterestBearingConfig and register with Light Token
allowed-tools: Bash, Read, Write, Edit, Glob, Grep, WebFetch, AskUserQuestion, Task, TaskCreate, TaskGet, TaskList, TaskUpdate, TaskOutput, mcp__deepwiki, mcp__zkcompression
---

## Create a Token-2022 mint with InterestBearingConfig and register with Light Token

Context:
- Guide: https://zkcompression.com/light-token/extensions/interest-bearing-tokens
- Skills and resources index: https://zkcompression.com/skill.md
- SPL to Light reference: https://zkcompression.com/api-reference/solana-to-light-comparison
- Packages: @lightprotocol/compressed-token, @lightprotocol/stateless.js, @solana/spl-token

SPL equivalent: createInitializeInterestBearingMintInstruction()
Light Token: createInitializeInterestBearingMintInstruction() + LightTokenProgram.createSplInterface()

### 1. Index project
- Grep `@solana/spl-token|Connection|Keypair|InterestBearing|TOKEN_2022` across src/
- Glob `**/*.ts` for project structure
- Identify: RPC setup, existing mint logic, entry point for T22 mint with interest bearing
- Task subagent (Grep/Read/WebFetch) if project has multiple packages to scan in parallel

### 2. Read references
- WebFetch the guide above — follow the Instruction tab for the full flow
- WebFetch skill.md — check for a dedicated skill and resources matching this task
- TaskCreate one todo per phase below to track progress

### 3. Clarify intention
- AskUserQuestion: what is the goal? (new T22 mint with interest bearing, register existing T22 mint, migrate existing SPL code)
- AskUserQuestion: does the project already use Token-2022?
- Summarize findings and wait for user confirmation before implementing

### 4. Create plan
- Based on steps 1–3, draft an implementation plan: which files to modify, what code to add, dependency changes
- Verify existing connection/signer setup is compatible with the cookbook prerequisites
- If anything is unclear or ambiguous, loop back to step 3 (AskUserQuestion)
- Present the plan to the user for approval before proceeding

### 5. Implement
- Add deps if missing: Bash `npm install @lightprotocol/compressed-token @lightprotocol/stateless.js @solana/spl-token`
- Create T22 mint: getMintLen([ExtensionType.InterestBearingConfig]) → SystemProgram.createAccount → createInitializeInterestBearingMintInstruction → createInitializeMint2Instruction
- Register with Light Token: LightTokenProgram.createSplInterface({ mint, tokenProgramId: TOKEN_2022_PROGRAM_ID })
- Transfer: createTransferInterfaceInstructions() from @lightprotocol/compressed-token/unified
- Write/Edit to create or modify files
- TaskUpdate to mark each step done

### 6. Verify
- Bash `tsc --noEmit`
- Bash run existing test suite if present
- TaskUpdate to mark complete

### Tools
- mcp__zkcompression__SearchLightProtocol("<query>") for API details
- mcp__deepwiki__ask_question("Lightprotocol/light-protocol", "<q>") for architecture
- Task subagent with Grep/Read/WebFetch for parallel lookups
- TaskList to check remaining work

Related Guides

Transfer interface

Wrap and unwrap

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