Rent Exemption Compatibility

Solayer Chain uses 1% of Solana’s rent for account storage, making it 99% cheaper to create accounts. However, this difference requires developers to use the correct instructions to avoid overpaying rent when creating tokens and accounts.

Why This Matters

Solana programs can fetch rent in two ways:

Method	Behavior	Result on Solayer Chain
`Rent::get()` syscall	Fetches rent from runtime	Correct - uses Solayer Chain’s 1% rent
`Rent::default()`	Uses hardcoded Solana values	Wrong - charges 100x too much

Instructions that rely on the Rent sysvar account internally use Rent::from_account_info(), which behaves like Rent::default() and returns Solana’s hardcoded rent values. This causes 100x overpayment on Solayer Chain.

Token Program Instructions

The original Token Program includes both legacy instructions (which use the Rent sysvar) and newer variants (which use the Rent::get() syscall).

Instructions to Avoid

Instruction	Issue
`InitializeMint`	Requires Rent sysvar, uses hardcoded rent
`InitializeAccount`	Requires Rent sysvar, uses hardcoded rent
`InitializeMultisig`	Requires Rent sysvar, uses hardcoded rent

Recommended Instructions

Instruction	Benefit
`InitializeMint2`	Uses `Rent::get()` syscall, correct rent calculation
`InitializeAccount2`	Uses `Rent::get()` syscall, correct rent calculation
`InitializeAccount3`	Uses `Rent::get()` syscall, most efficient variant
`InitializeMultisig2`	Uses `Rent::get()` syscall, correct rent calculation

Token 2022 Instructions

Token 2022 (Token Extensions) follows the same pattern. Always use the “V2” or “V3” variants.

Instructions to Avoid

Instruction	Issue
`InitializeMint`	Requires Rent sysvar
`InitializeAccount`	Requires Rent sysvar
`InitializeMultisig`	Requires Rent sysvar

Recommended Instructions

Instruction	Benefit
`InitializeMint2`	Uses `Rent::get()` syscall
`InitializeAccount2`	Uses `Rent::get()` syscall
`InitializeAccount3`	Uses `Rent::get()` syscall, most efficient
`InitializeMultisig2`	Uses `Rent::get()` syscall

Important for Token 2022: Account sizes vary based on enabled extensions. Always calculate sizes dynamically rather than hardcoding values.

Code Examples

Creating a Mint with InitializeMint2 (TypeScript)

import {
  Connection,
  Keypair,
  SystemProgram,
  Transaction,
} from "@solana/web3.js";
import {
  TOKEN_PROGRAM_ID,
  MINT_SIZE,
  createInitializeMint2Instruction,
} from "@solana/spl-token";

async function createMint(
  connection: Connection,
  payer: Keypair,
  mintAuthority: PublicKey,
  decimals: number
): Promise<PublicKey> {
  const mint = Keypair.generate();

  // Query rent from the chain - gets Solayer Chain's correct rent
  const lamports = await connection.getMinimumBalanceForRentExemption(MINT_SIZE);

  const transaction = new Transaction().add(
    SystemProgram.createAccount({
      fromPubkey: payer.publicKey,
      newAccountPubkey: mint.publicKey,
      space: MINT_SIZE,
      lamports, // Correct rent from chain
      programId: TOKEN_PROGRAM_ID,
    }),
    // Use InitializeMint2, NOT InitializeMint
    createInitializeMint2Instruction(
      mint.publicKey,
      decimals,
      mintAuthority,
      null, // freeze authority
      TOKEN_PROGRAM_ID
    )
  );

  await sendAndConfirmTransaction(connection, transaction, [payer, mint]);
  return mint.publicKey;
}

Creating a Token Account with InitializeAccount3 (TypeScript)

import {
  Connection,
  Keypair,
  PublicKey,
  SystemProgram,
  Transaction,
} from "@solana/web3.js";
import {
  TOKEN_PROGRAM_ID,
  ACCOUNT_SIZE,
  createInitializeAccount3Instruction,
} from "@solana/spl-token";

async function createTokenAccount(
  connection: Connection,
  payer: Keypair,
  mint: PublicKey,
  owner: PublicKey
): Promise<PublicKey> {
  const account = Keypair.generate();

  // Query rent from the chain
  const lamports = await connection.getMinimumBalanceForRentExemption(ACCOUNT_SIZE);

  const transaction = new Transaction().add(
    SystemProgram.createAccount({
      fromPubkey: payer.publicKey,
      newAccountPubkey: account.publicKey,
      space: ACCOUNT_SIZE,
      lamports,
      programId: TOKEN_PROGRAM_ID,
    }),
    // Use InitializeAccount3 for best efficiency
    createInitializeAccount3Instruction(
      account.publicKey,
      mint,
      owner,
      TOKEN_PROGRAM_ID
    )
  );

  await sendAndConfirmTransaction(connection, transaction, [payer, account]);
  return account.publicKey;
}

Token 2022 with Extensions (TypeScript)

import {
  Connection,
  Keypair,
  SystemProgram,
  Transaction,
} from "@solana/web3.js";
import {
  TOKEN_2022_PROGRAM_ID,
  ExtensionType,
  getMintLen,
  createInitializeMint2Instruction,
  createInitializeTransferFeeConfigInstruction,
} from "@solana/spl-token";

async function createMintWithTransferFee(
  connection: Connection,
  payer: Keypair,
  mintAuthority: PublicKey,
  decimals: number,
  feeBasisPoints: number,
  maxFee: bigint
): Promise<PublicKey> {
  const mint = Keypair.generate();

  // Calculate size dynamically based on extensions
  const extensions = [ExtensionType.TransferFeeConfig];
  const mintLen = getMintLen(extensions);

  // Query rent for the dynamic size
  const lamports = await connection.getMinimumBalanceForRentExemption(mintLen);

  const transaction = new Transaction().add(
    SystemProgram.createAccount({
      fromPubkey: payer.publicKey,
      newAccountPubkey: mint.publicKey,
      space: mintLen, // Dynamic size
      lamports,       // Correct rent from chain
      programId: TOKEN_2022_PROGRAM_ID,
    }),
    // Initialize extension BEFORE mint
    createInitializeTransferFeeConfigInstruction(
      mint.publicKey,
      mintAuthority,
      mintAuthority,
      feeBasisPoints,
      maxFee,
      TOKEN_2022_PROGRAM_ID
    ),
    // Use InitializeMint2
    createInitializeMint2Instruction(
      mint.publicKey,
      decimals,
      mintAuthority,
      null,
      TOKEN_2022_PROGRAM_ID
    )
  );

  await sendAndConfirmTransaction(connection, transaction, [payer, mint]);
  return mint.publicKey;
}

Rust: Correct vs Incorrect Rent Usage

When writing custom Solana programs, always use Rent::get() instead of Rent::default().

use solana_program::rent::Rent;
use solana_program::sysvar::Sysvar;

// CORRECT: Uses syscall to fetch rent from runtime
fn get_rent_correct() -> Result<Rent, ProgramError> {
    Rent::get()
}

// INCORRECT: Returns hardcoded Solana rent values
fn get_rent_wrong() -> Rent {
    Rent::default() // DO NOT USE - ignores Solayer Chain's rent
}

Best Practices Summary

Always query rent from the chain

const lamports = await connection.getMinimumBalanceForRentExemption(size);

Use “V2” or “V3” instruction variants - They use the Rent::get() syscall internally
Calculate account sizes dynamically for Token 2022 - Use getMintLen() and getAccountLen() with your extensions
In Rust programs, use Rent::get() - Never use Rent::default() which returns hardcoded values

Quick Reference

Safe Instructions (use `Rent::get()` syscall)

InitializeMint2
InitializeAccount2
InitializeAccount3
InitializeMultisig2

Instructions to Avoid (use Rent sysvar)

InitializeMint
InitializeAccount
InitializeMultisig

By following these guidelines, your applications will correctly use Solayer Chain’s 99% cheaper rent and avoid overpaying for account creation.

Introduction

API Reference

System Architecture

Advanced Features

Block Propagation

Consensus

Run a Node

LAYER Staking

Solayer Bridge

Historical Data Access

Rent Exemption Compatibility

Why This Matters

Token Program Instructions

Instructions to Avoid

Recommended Instructions

Token 2022 Instructions

Instructions to Avoid

Recommended Instructions

Code Examples

Creating a Mint with InitializeMint2 (TypeScript)

Creating a Token Account with InitializeAccount3 (TypeScript)

Token 2022 with Extensions (TypeScript)

Rust: Correct vs Incorrect Rent Usage

Best Practices Summary

Quick Reference

Safe Instructions (use `Rent::get()` syscall)

Instructions to Avoid (use Rent sysvar)

​Why This Matters

​Token Program Instructions

​Instructions to Avoid

​Recommended Instructions

​Token 2022 Instructions

​Instructions to Avoid

​Recommended Instructions

​Code Examples

​Creating a Mint with InitializeMint2 (TypeScript)

​Creating a Token Account with InitializeAccount3 (TypeScript)

​Token 2022 with Extensions (TypeScript)

​Rust: Correct vs Incorrect Rent Usage

​Best Practices Summary

​Quick Reference

​Safe Instructions (use Rent::get() syscall)

​Instructions to Avoid (use Rent sysvar)

Why This Matters

Token Program Instructions

Instructions to Avoid

Recommended Instructions

Token 2022 Instructions

Instructions to Avoid

Recommended Instructions

Code Examples

Creating a Mint with InitializeMint2 (TypeScript)

Creating a Token Account with InitializeAccount3 (TypeScript)

Token 2022 with Extensions (TypeScript)

Rust: Correct vs Incorrect Rent Usage

Best Practices Summary

Quick Reference

Safe Instructions (use `Rent::get()` syscall)

Instructions to Avoid (use Rent sysvar)