How do I check buy and sell tax on a Base token?

Why separate buy and sell tax

A token can allow both directions but charge very different amounts. A low buy tax does not imply a low sell tax, and transfer behavior can change if contract parameters are mutable.

For trading decisions, the sell side is especially important because a token that can technically be sold may still impose economically damaging exit costs.

How Jepeta represents tax data

Jepeta reads token-security data from GoPlus. The V4 compatibility contract calls the fields buy_tax_percent and sell_tax_percent; V5 carries corresponding observations in normalized evidence. Unavailable values remain explicitly unknown rather than being displayed as reassuring zeroes.

The decision policy can warn on elevated taxes. Tax fields sit beside honeypot, mintability, holder concentration, liquidity, and data quality so the user does not over-focus on one number.

Interpretation rule

Use tax as one input. Confirm the token contract, source freshness, liquidity depth, and whether the token has permissions that could change fees later.

A permanent evidence page is useful for seeing what was observed at a published timestamp; run a fresh scan before relying on the current tax state.

A numerical example isolates the fee

With synthetic inputs, a 2% token fee on a 100-unit transfer leaves 98 units before other costs; a 20% fee leaves 80. The calculation is 100 × (1 − fee / 100). This does not include price movement, route slippage, gas or a second taxable transfer, and it is not a quote for a real token. Check whether a provider expresses its raw value as a ratio or percentage before comparing it with Jepeta’s documented percentage fields.

Practical checklist

• Check buy and sell separately
• Treat null as unknown
• Watch for asymmetric exit cost
• Check whether fees can change
• Re-scan before execution

Limitations