> For the complete documentation index, see [llms.txt](https://docs.keystonefi.xyz/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.keystonefi.xyz/keystone-finance/deposit.md).

# Deposit

Deposit USDC into the ksUSD vault and receive `ksUSD` share tokens at the current share price.

> **New here?** Read [What is ksUSD?](/keystone-finance/reserve-asset.md) first.

***

## The instruction

```
deposit(usdc_amount: u64)
```

In one atomic transaction:

* Transfers USDC from the user into the vault's USDC ATA
* Mints `ksUSD` to the user at the current share price
* Updates vault NAV accounting

| Account              | Mutability | Purpose                                   |
| -------------------- | ---------- | ----------------------------------------- |
| `vault`              | mut        | Vault PDA (seeds: `[b"vault"]`)           |
| `vault_usdc_account` | mut        | Vault's USDC ATA — receives the deposit   |
| `ksusd_mint`         | mut        | ksUSD share mint — vault PDA is authority |
| `user_usdc_account`  | mut        | Depositor's USDC source ATA               |
| `user_ksusd_account` | mut        | Depositor's ksUSD destination ATA         |
| `user`               | signer     | Depositor                                 |
| `token_program`      | —          | SPL token program                         |

***

## Share-price math

```
share_price_1e9 = (cached_nav_usdc × 1e9) / max(total_shares, 1)
shares_to_mint  = (usdc_amount × 1e9 / share_price_1e9) / 1_000     // ksUSD has 6 decimals
```

* **First deposit** into an empty vault mints `usdc_amount` shares 1:1 at $1.00 (initial `share_price_1e9 = 1_000_000_000`)
* **Every subsequent deposit** mints fewer shares as the share price drifts upward with accrued carry

***

## Guardrails

* **Vault must not be paused.** Admin can pause via `set_pause` for emergency response.
* **Deposit cap.** New deposits revert if `cached_nav_usdc + usdc_amount > deposit_cap_usdc` (default: $1M cap on launch).
* **No zero deposits.** `usdc_amount > 0` required.

***

## TypeScript example

```ts
import { Program, BN } from "@coral-xyz/anchor";
import { PublicKey } from "@solana/web3.js";
import { TOKEN_PROGRAM_ID, getAssociatedTokenAddressSync } from "@solana/spl-token";

const PROGRAM_ID = new PublicKey("HvsAc157bJ7Pd4uGr7xssHMifGs6RMbPu14ZMsiEABWT");

const [vaultPda] = PublicKey.findProgramAddressSync(
  [Buffer.from("vault")],
  PROGRAM_ID
);

const vault = await program.account.vault.fetch(vaultPda);
const userUsdcAta  = getAssociatedTokenAddressSync(vault.usdcMint,  user.publicKey);
const userKsusdAta = getAssociatedTokenAddressSync(vault.ksusdMint, user.publicKey);
const vaultUsdcAta = getAssociatedTokenAddressSync(vault.usdcMint,  vaultPda, true);

const tx = await program.methods
  .deposit(new BN("100_000_000"))         // 100 USDC (6 decimals)
  .accountsStrict({
    vault: vaultPda,
    vaultUsdcAccount: vaultUsdcAta,
    ksusdMint: vault.ksusdMint,
    userUsdcAccount: userUsdcAta,
    userKsusdAccount: userKsusdAta,
    user: user.publicKey,
    tokenProgram: TOKEN_PROGRAM_ID,
  })
  .rpc();
```

***

## Events

`DepositEvent` is emitted on success:

```rust
pub struct DepositEvent {
    pub user: Pubkey,
    pub usdc_amount: u64,
    pub shares_minted: u64,
    pub share_price_1e9: u64,
    pub new_total_shares: u64,
    pub timestamp: i64,
}
```

***

## Related

* [Withdraw](/keystone-finance/withdraw.md) — instant vs. queued paths
* [Check position & NAV](/keystone-finance/check-position.md)
* [NAV & share pricing](/reference/nav-calculation.md)
* [Errors](/for-developers/errors.md)


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