# Extra currencies (https://docs.ton.org/llms/foundations/extra-currencies/content.md)



TON supports up to $2^{32}$ *extra currencies* besides its native currency — Gram. They are protocol-level fungible assets stored alongside [Gram](https://docs.ton.org/llms/foundations/glossary/content.md) in account balances. Extra currencies can be similarly attached to internal messages, but they cannot be used to pay [transfer fees](#transfers-and-fees) in place of Gram.

Unlike [jettons](https://docs.ton.org/llms/contracts/standard/tokens/jettons/overview/content.md), extra currencies cannot have custom behavior — they can only be stored and transferred. Furthermore, [minting of new extra currencies](#minting) is controlled by the masterchain [config](https://docs.ton.org/llms/foundations/config/content.md).

<Callout type="note" title="Mainnet status">
  There are no active extra currencies on the mainnet — use jettons to create new fungible tokens.
</Callout>

## Representation [#representation]

The [`block.tlb` schema](https://docs.ton.org/llms/foundations/tlb/overview/content.md) defines an extra-currency collection as a dictionary, which is then kept in the `CurrencyCollection` structure next to the Gram balance:

```tlb
extra_currencies$_ dict:(HashmapE 32 (VarUInteger 32))
                 = ExtraCurrencyCollection;
currencies$_ grams:Grams other:ExtraCurrencyCollection
           = CurrencyCollection;
```

Each 32-bit dictionary key is a currency ID. Each value is a positive integer of at most 248 bits — zero balances are omitted.

## Transfers and fees [#transfers-and-fees]

A contract reads its remaining `CurrencyCollection` balance through [TVM](https://docs.ton.org/llms/tvm/overview/content.md) and specifies extra-currency amounts in an outbound internal message. The action phase subtracts each amount from the account balance. An insufficient balance produces [action result code 38](https://docs.ton.org/llms/tvm/exit-codes/content.md).

Extra currencies cannot pay storage, computation, or message-forwarding fees. These fees remain denominated in Gram.

<Callout type="note">
  Since [global TVM version 10](https://docs.ton.org/llms/foundations/config/content.md), [send modes 64 and 128](https://docs.ton.org/llms/foundations/messages/modes/content.md) change only the Gram component of a message. They do not add extra currencies from the incoming message or account balance.
</Callout>

<Callout type="note">
  Incoming and outgoing *external* messages cannot carry any currencies.
</Callout>

## Minting [#minting]

Extra-currency minting is controlled by the masterchain configuration:

* [Parameter 7](https://docs.ton.org/llms/foundations/config/content.md) stores target amounts by currency ID.
* [Parameter 2](https://docs.ton.org/llms/foundations/config/content.md) identifies the minter account. [Parameter 0](https://docs.ton.org/llms/foundations/config/content.md) is the fallback when parameter 2 is absent.
* [Parameter 6](https://docs.ton.org/llms/foundations/config/content.md) stores two Gram price fields intended for minting governance. The collator does not use them to calculate the minted amount.

For each parameter 7 entry, a masterchain collator subtracts the previous masterchain state's global balance from the configured target. A positive difference for a nonzero currency ID is minted in that masterchain block. An equal or lower target mints nothing — lowering the target does not burn currency.

When the difference is positive, the block contains a special internal message from the zero masterchain address to the minter account. Its `CurrencyCollection` carries the minted extra currencies, and its body is empty. Validators recompute the difference and reject a block whose minted value or special message does not match the configuration.

Changing a mint target requires a [configuration update](https://docs.ton.org/llms/foundations/config/content.md). A contract cannot create extra currency through a TVM instruction.