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Overview

Token-2022 is Solana’s next-generation token program. It supports extensions that add new behaviors to tokens - including a transfer fee extension that automatically deducts a percentage of each transfer. The Umbra SDK fully supports Token-2022 mints, including those with transfer fee extensions.

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Transfer Fees

When you deposit a Token-2022 token that has a transfer fee configured, the fee is deducted by the Token-2022 program before tokens reach the shielded pool. The SDK accounts for this by:
  1. Fetching the mint account to detect the TransferFeeConfig extension
  2. Calling the epoch info provider to determine the current epoch
  3. Selecting the applicable fee schedule (Token-2022 supports epoch-based fee changes)
  4. Computing actualReceived = amount - transferFee
  5. Applying Umbra protocol fees on top of actualReceived
The amount credited to your ETA is actualReceived - protocolFees.

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Epoch Info Provider

Transfer fee schedule selection requires knowing the current Solana epoch. This is why epochInfoProvider is part of the IUmbraClient interface - it is fetched once per deposit operation for Token-2022 mints. For standard SPL tokens (Token program), the epoch info provider is not called. The provider defaults to an RPC-based implementation constructed from rpcUrl. You can override it if needed: 
import {
  getUmbraClientFromSigner,
  getRpcBasedEpochInfoProvider,
} from "@umbra-privacy/sdk";

const client = await getUmbraClientFromSigner(
  { signer, network, rpcUrl, rpcSubscriptionsUrl },
  {
    // Custom epoch info provider (e.g., for testing with a fixed epoch)
    epochInfoProvider: async () => ({
      epoch: 500n,
      slotIndex: 0n,
      slotsInEpoch: 432000n,
      absoluteSlot: 216000000n,
      blockHeight: 210000000n,
    }),
  }
);

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Fee Calculation

The SDK uses the same fee calculation as the Token-2022 program: 
transferFee = min(
  floor(amount × feeBasisPoints / 10_000),
  maximumFee
)
Where feeBasisPoints and maximumFee are read from the epoch-appropriate fee schedule in the mint’s TransferFeeConfig extension.

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No Special Configuration Required

You do not need to do anything special to use Token-2022 mints. Simply pass the Token-2022 mint address as you would any other mint: 
const TOKEN22_MINT = "TokenMintAddressHere...";

const deposit = getDirectDepositIntoEncryptedBalanceFunction({ client });
const signature = await deposit(client.signer.address, TOKEN22_MINT, 1_000_000n);
The SDK detects that the mint is a Token-2022 program account, checks for a transfer fee extension, and handles the fee deduction automatically.

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Affected Operations

Transfer fee handling applies to these operations:
  • getDirectDepositIntoEncryptedBalanceFunction - fetches epoch info only when a Token-2022 transfer fee is detected
  • getCreateSelfClaimableUtxoFromPublicBalanceFunction - same
  • getCreateReceiverClaimableUtxoFromPublicBalanceFunction - same
Operations that draw from an encrypted balance (ETA) rather than a public ATA are not affected by Token-2022 transfer fees, because the transfer happens within the Umbra program and does not cross the Token-2022 transfer fee boundary.