Taproot activation proposal 202102

Expected timeline:

• 2021 March 17-31: Full node software released with Taproot activation deployment.
• 2021 July 23: Economic majority has upgraded. Miner signalling begins to indicate preparedness to protect the economic minority who haven’t upgraded yet.
• 2 weeks after 90% of hashrate signals: Taproot activates. Economic majority enforces, while miners protect the economic minority until they upgrade as well.
• 2022 August 1: Entire economy has upgraded.

For explanations of the various parameters, see BIP 8.

name=taproot

• Rationale: Already used in Bitcoin Core (for Signet and tests), no reason to change (BIP8’s “bipN” recommendation not applicable due to 2 Taproot BIPs)

bit=2

• Rationale: Already used in Bitcoin Core (for tests), no reason to change
• Note: Bit 2 is unaffected by ongoing miner ASICBoost false-bit-spam.

startheight=693504 (~2021 July 23rd)

• Rationale 1:
• * Earliest activation (MASF) takes 4 weeks, coinciding with Bitcoin Core 0.20 Maintenance End. Therefore, a backport of Taproot to 0.20 (complex and would need validation) can be avoided.
• Rationale 2:
• * ~26 weeks (6.5 months) between meeting and earliest activation.
• * 1.5 months to prepare and release activation + 5 months for the economic majority to upgrade.

timeoutheight=745920 (~2022 July 22nd / 1 year after signalling begins)

• Rationale:
• * Plenty of time and community support.
• * Remaining economic minority can be expected to upgrade within a year.

lockinontime= NO CONSENSUS WAS REACHED

threshold=1815 (90%)

• Rationale 1:
• * High enough to ensure the Taproot chain always has a lead ahead of any invalid chains.
• Rationale 2:
• * Low enough to avoid a sudden malicious stall of activation by rented or unknown miners.
• * 90% of hashrate has already committed to work toward Taproot activation.