Add draft-aphelionz-marginal-fee: Reduce Marginal Fee to 1000 Zatoshis by aphelionz · Pull Request #1352 · zcash/zips

aphelionz · 2026-08-17T19:33:46Z

Adds a draft ZIP proposing a reduction of ZIP 317's marginal_fee from 5,000 to 1,000 zatoshis per logical action. The conventional fee for a minimal 2-action transaction goes from 10,000 to 2,000 zatoshis; no other ZIP 317 parameter or formula changes.

This is a wallet convention and node relay policy change, so it requires no consensus change and no network upgrade.

ValarDragon · 2026-08-17T19:59:47Z

Very in favor of this. I'd even support going lower than 1000 zats, to 500 zats/action.

Big proponent of the October 1st target as well.

Proposes reducing ZIP 317's marginal_fee from 5,000 to 1,000 zatoshis per logical action, lowering the minimal 2-action conventional fee from 10,000 to 2,000 zatoshis. No other ZIP 317 parameter or formula changes. This is a wallet convention and node relay policy change, so it requires no consensus change and no network upgrade. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Co-authored-by: Kris Nuttycombe <kris@nutty.land>

Co-authored-by: Daira-Emma Hopwood <daira@jacaranda.org>

Per review: as an update ZIP, the specification gives the exact table entry being replaced rather than describing the change. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

The ZIP editors asked for the weight_ratio_cap change to be made simultaneously with the marginal fee reduction. This removes the cap rather than raising it to 10: selection weight becomes proportional to fee, and the block-space argument in ZIP 317's rationale is independent of the cap and carries on its own. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Per review: a height is more useful for coordination. Height 3500000 falls in late September 2026 at 75-second block spacing, matching the prior 2026-10-01 target. The milestone table is dropped. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Per review: wallets updating at different times are distinguishable by fee. The mitigation is the shared activation height. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Per review: no change to the ZIP 401 low_fee_penalty is required; it is defined independently of marginal_fee. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Per review: the operator-revert sentence was unclear, and mandating revert machinery adds logic for a case better handled by a follow-on ZIP if it ever arises. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Per review: this ZIP proposes no dynamic fee, and alternatives do not belong in the rationale. The power-of-10 paragraph is deleted; the 500, 100, and no-change options move to a new Alternatives section. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Per review. States the fee-independent deterrents and the 3.1x cost factor relative to the design point, without the dollars-per-hour arithmetic. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

The endpoint that shipped in zebra 6.3.0 returns the ZIP 317 marginal_fee directly; the synthetic-fill estimator it describes was never released. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

A 2,000-zatoshi transaction has 2 unpaid actions under the old parameters, so producers configured with block_unpaid_action_limit = 0 exclude it; the prior wording claimed it is mined unconditionally. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

ZEC last held $800 on 2026-08-29; it is higher at time of writing, but that may not hold. Derived figures update: 26.7 P, $0.0800 / $0.0160, and 5.3x the design-point cost. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Below-conventional-fee transactions are penalized and may be excluded from blocks at non-upgraded nodes, so the ordering is a requirement, not a preference. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author pass: plainer motivation without the ratio table, shorter abstract, privacy, rationale, and deployment sections. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Merges the two overlapping paragraphs: node updates are uncoordinated and immediate, wallet adoption waits for the activation height, and the ordering is a MUST because non-upgraded producers exclude the new fee. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

nuttycom · 2026-09-08T20:25:10Z

+*Security:* `grace_actions` and `block_unpaid_action_limit` still
+bound unpaid actions per block, and ZIP 401 [^zip-0401] mempool cost
+limiting still bounds memory.


This doesn't need to be here.

Addressed in 89a0a47

nuttycom · 2026-09-08T20:36:45Z

+Relay policy and block template updates MUST ship before wallets adopt the new
+fee: a 2,000-zatoshi transaction counts 2 unpaid actions under the old parameters,
+and producers configured with `block_unpaid_action_limit = 0` will not mine it.
+Node operators need no coordination and SHOULD update as soon as releases are
+available.


This presents a coordination problem, given the height specified below. There is no end-of-service halt that would enforce that nodes upgrade to allow relay of these lower-fee transactions, so it would require a coordinated rollout to relaying nodes.

In the discussion surrounding this, we discovered that the current minimum relay fee is implementation-defined, and needs to be specified.

The deadline below should be shifted to a date after the end-of-service halt of node versions that are active on the network at the time that this ZIP transitions to Proposed status.

Addressed in 697888c

aphelionz force-pushed the aphelionz/marginal-fee-zip branch 2 times, most recently from d141e0c to a820a55 Compare August 17, 2026 19:53

ValarDragon reviewed Aug 17, 2026

View reviewed changes