CPI to the System Program

The System Program handles account creation, assignment, allocation, and lamport transfers. Most programs CPI to it for rent payment and SOL movement.

Recipe

invoke(
  &system_instruction::transfer(from.key, to.key, amount),
  &[from.clone(), to.clone()],
)?;

When to reach for this:

Paying rent for new accounts.
Moving SOL to treasury or users.
Closing accounts and returning rent.

Working Example

let rent = Rent::get()?;
let lamports = rent.minimum_balance(space);
invoke(
  &system_instruction::create_account(payer.key, new.key, lamports, space as u64, owner),
  &[payer.clone(), new.clone(), system_program.clone()],
)?;

What this demonstrates:

Rent sysvar for minimum balance.
create_account sets owner program.
Payer signs transfer/create.

Deep Dive

Common Instructions

IX	Purpose
transfer	Move lamports
create_account	Allocate + assign
allocate	Add space
assign	Change owner (restricted)

Rust Notes

use solana_program::system_program;

Gotchas

Transfer from PDA without signed - Fails. Fix: invoke_signed.
Create on existing - Fails if lamports > 0. Fix: Check empty account.
Insufficient lamports - Transfer/create fails. Fix: Balance checks.
Wrong owner param - Account stuck wrong owner. Fix: Pass your program id.
Rent not exempt - Under-funding a new account fails the transaction with InsufficientFundsForRent; the runtime enforces rent exemption at creation. (Rent collection/reaping is no longer active, so the failure is up front, not later.) Fix: Fund Rent::get()?.minimum_balance(space).

Alternatives

Alternative	Use When	Don't Use When
Client creates account	Simpler program	PDA flows
Anchor init	Abstracts	Native
transfer_with_seed	Derived addresses	PDA preferred

FAQs

System program id?

11111111111111111111111111111111

Create + init same tx?

Yes.

Close account?

Transfer all lamports out.

Assign CPI?

Rare - security sensitive.

allocate vs create?

create for new keys.

PDA create?

invoke_signed.

Rent sysvar?

Rent::get() in program.

Zero lamports transfer?

Allowed but pointless.

Signer for transfer?

From account signer.

Multi transfer?

Multiple CPIs ok.

Agave 4.1.1?

Match system_instruction helpers.

Surfpool?

Test rent math.

Stack versions: This page was written for Agave 4.1.1, Solana CLI 3.0.10, Anchor 0.32.1, anchor-lang 0.32.1, Rust 1.91.1, @solana/kit 7.0.0, Surfpool 0.12.0, and LiteSVM 0.6.x.

Recipe

invoke(
  &system_instruction::transfer(from.key, to.key, amount),
  &[from.clone(), to.clone()],
)?;

When to reach for this:

Paying rent for new accounts.
Moving SOL to treasury or users.
Closing accounts and returning rent.

Working Example

let rent = Rent::get()?;
let lamports = rent.minimum_balance(space);
invoke(
  &system_instruction::create_account(payer.key, new.key, lamports, space as u64, owner),
  &[payer.clone(), new.clone(), system_program.clone()],
)?;

What this demonstrates:

Rent sysvar for minimum balance.
create_account sets owner program.
Payer signs transfer/create.

Deep Dive

Common Instructions

IX	Purpose
transfer	Move lamports
create_account	Allocate + assign
allocate	Add space
assign	Change owner (restricted)

Rust Notes

use solana_program::system_program;

Gotchas

Transfer from PDA without signed - Fails. Fix: invoke_signed.
Create on existing - Fails if lamports > 0. Fix: Check empty account.
Insufficient lamports - Transfer/create fails. Fix: Balance checks.
Wrong owner param - Account stuck wrong owner. Fix: Pass your program id.
Rent not exempt - Under-funding a new account fails the transaction with InsufficientFundsForRent; the runtime enforces rent exemption at creation. (Rent collection/reaping is no longer active, so the failure is up front, not later.) Fix: Fund Rent::get()?.minimum_balance(space).

Alternatives

Alternative	Use When	Don't Use When
Client creates account	Simpler program	PDA flows
Anchor init	Abstracts	Native
transfer_with_seed	Derived addresses	PDA preferred

FAQs

System program id?

11111111111111111111111111111111

Create + init same tx?

Yes.

Close account?

Transfer all lamports out.

Assign CPI?

Rare - security sensitive.

allocate vs create?

create for new keys.

PDA create?

invoke_signed.

Rent sysvar?

Rent::get() in program.

Zero lamports transfer?

Allowed but pointless.

Signer for transfer?

From account signer.

Multi transfer?

Multiple CPIs ok.

Agave 4.1.1?

Match system_instruction helpers.

Surfpool?

Test rent math.

Stack versions: This page was written for Agave 4.1.1, Solana CLI 3.0.10, Anchor 0.32.1, anchor-lang 0.32.1, Rust 1.91.1, @solana/kit 7.0.0, Surfpool 0.12.0, and LiteSVM 0.6.x.

CPI to the System Program

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CPI to the System Program