How does Phantom handle Priority Fees?

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When does Phantom apply priority fees to Solana transactions?

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Phantom will calculate and apply Priority Fees to all dApp-generated transactions, provided:
• The transaction(s) do not already have signature(s) present
• The transaction(s) do not have existing priority fee instructions (computeUnitBudget or computeUnitLimit)
• After enhancing transaction(s) with Priority Fees, the size of each transaction will still be less than the byte size limit (1232 bytes)

If you do not want Phantom (or any other wallet) to add priority fees, we recommend that you partially-sign the transaction.

For more info, check out our docs on Priority Fees: https://docs.phantom.app/developer-powertools/solana-priority-fees