> For the complete documentation index, see [llms.txt](https://phantazm.gitbook.io/phantazm-1/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://phantazm.gitbook.io/phantazm-1/the-core-protocol/debt-tokens.md).

# Debt Tokens

Debt tokens are interest-accruing tokens that are minted and burned on [`borrow`](/phantazm-1/the-core-protocol/lendingpool.md#borrow) and [`repay`](/phantazm-1/the-core-protocol/lendingpool.md#repay), representing the debt owed by the token holder. There are 2 types of debt tokens:

* Stable debt tokens, representing a debt to the protocol with a stable interest rate
* Variable debt tokens, representing a debt to the protocol with a variable interest rate

## EIP20 Methods

Although debt tokens are modelled on the ERC20/EIP20 standard, they are non-transferrable. Therefore they do not implement any of the standard ERC20/EIP20 functions relating to `transfer()` and `allowance()`.

{% hint style="info" %}
`balanceOf()` will always return the most up to date accumulated debt of the user.
{% endhint %}

{% hint style="info" %}
`totalSupply()` will always return the most up to date total debt accrued by all protocol users for *that specific type (stable vs variable) of debt token*.
{% endhint %}

## Shared Methods

### UNDERLYING\_ASSET\_ADDRESS()

**`function UNDERLYING_ASSET_ADDRESS()`**

Returns the underlying asset of the debt token.

### POOL()

**`function POOL()`**

Returns the address of the associated [`LendingPool`](/phantazm-1/the-core-protocol/lendingpool.md) for the debt token.

### approveDelegation\*\*()\*\*

**`function approveDelegation(address delegatee, uint256 amount)`**

Sets the `amount` of allowance for `delegatee` to borrow of a particular debt token.

Used in [credit delegation](broken://pages/VCPdGkN7wcDG0P6TRT2Q).

| Parameter Name | Type      | Description                           |
| -------------- | --------- | ------------------------------------- |
| `delegatee`    | address   | the user receiving the allowance      |
| `amount`       | `uint256` | the allowance amounts given to `user` |

### borrowAllowance\*\*()\*\*

**`function borrowAllowance(address fromUser, address toUser)`**

Returns the borrow allowance `toUser` has been given by `fromUser`.

Used in [credit delegation](broken://pages/VCPdGkN7wcDG0P6TRT2Q).

| Parameter Name | Type    | Description                      |
| -------------- | ------- | -------------------------------- |
| `fromUser`     | address | the user giving allowance        |
| `toUser`       | address | the user receiving the allowance |

Returns the current allowance of `toUser` for a particular debt token.

## Stable Debt Methods

### getSupplyData\*\*()\*\*

**`function getSupplyData()`**

Returns the supply / deposit data for the debt token.

#### Return values

| Type    | Description                      |
| ------- | -------------------------------- |
| uint256 | principal supply                 |
| uint256 | total supply                     |
| uint256 | average borrow rate              |
| uint40  | timestamp for last supply update |

### getTotalSupplyAndAvgRate\*\*()\*\*

**`function getTotalSupplyAndAvgRate()`**

Returns the total supply and average stable rate of the token.

#### Return values

| Type    | Description         |
| ------- | ------------------- |
| uint256 | total supply        |
| uint256 | average stable rate |

### **principalBalanceOf()**

**`function principalBalanceOf(address user)`**

Returns the principal debt balance of the `user`.

### getUserLastUpdated\*\*()\*\*

**`function getUserLastUpdated(address user)`**

Returns the timestamp of the last action taken by `user` as `uint40`.

### getAverageStableRate\*\*()\*\*

**`function getAverageStableRate()`**

Returns the average stable rate across all the stable rate debt in the protocol as `uint256`.

### getUserStableRate\*\*()\*\*

**`function getUserStableRate(address user)`**

Returns the stable rate of `user` as `uint256`.

## Variable Debt Methods

### scaledBalanceOf\*\*()\*\*

**`function scaledBalanceOf(address user)`**

Returns the principal debt balance of `user`.

### scaledTotalSupply\*\*()\*\*

**`function scaledTotalSupply()`**

Returns the scaled total supply of the variable debt token.

This represents $$sum( borrows / index )$$ .

### getScaledUserBalanceAndSupply\*\*()\*\*

**`function getScaledUserBalanceAndSupply(address user)`**

Returns the principal balance of the `user` and principal total supply.

#### Return values

| Type    | Description               |
| ------- | ------------------------- |
| uint256 | principal balance of user |
| uint256 | principal total supply    |