The tax
Each Rainfall coin is a Token-2022 mint with two extensions: MetadataPointer (name, ticker and image live in the mint) and TransferFeeConfig. LaunchLab accepts no other extension, so a Rainfall coin has no transfer hook, no freeze authority and no mint authority.
How the fee is taken
On every TransferChecked the Token-2022 program computes amount × rate and keeps that part in the receiving token account, in a separate "withheld" balance. The receiver gets the rest. Nobody can spend withheld tokens except the withdraw-withheld authority. Anyone can move withheld amounts from accounts into the mint with harvestWithheldTokensToMint.
The rate is set at launch, from 1 % to 5 % in 0.5 point steps. The maximum fee per transfer is set to the whole supply, so the rate applies to transfers of any size.
Who holds which authority
| On the curve | After graduation | |
|---|---|---|
| Withdraw-withheld authority | Rainfall keeper (the platform's transfer_fee_extension_auth), from creation | Rainfall keeper |
| Transfer-fee config authority (can change the rate) | The LaunchLab authority PDA WLHv2UAZm6z4KyaaELi5pjdbJh6RESMva1Rnn8pJVVh; nobody can change the rate | Rainfall keeper, used only for melt steps the creator chose |
| Mint authority | None. Revoked at creation. | |
Checked on chain on 2026-11-10 against live LaunchLab coins with a transfer fee: during the curve the config authority is WLHv2UAZm6z4KyaaELi5pjdbJh6RESMva1Rnn8pJVVh and the withdraw authority is the platform's key; on graduated coins both are the platform's key.
What it costs a trader
A buy on the curve pays the curve fees (see Fees) and then the tax on the tokens received. A sell pays the tax on the tokens sent, then the curve fees. On the CPMM pool after graduation the tax adds to the pool fee: a 2 % coin on a 0.25 % pool costs about 2.25 % per swap leg.