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ZIP 317: Add Ironwood-pool Action fees as a revision to ZIP 317 #1314

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49be38e
ZIP 317: Remove the ZSA issuance and asset-creation fee contributions
nuttycom Jun 27, 2026
f90282f
ZIP 317: Introduce the revisions mechanism
nuttycom Jun 27, 2026
39703bc
ZIP 317: Add Revision 1 for the Ironwood network upgrade
nuttycom Jun 27, 2026
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4 changes: 2 additions & 2 deletions README.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -136,7 +136,7 @@ Released ZIPs
<tr> <td>301</td> <td class="left"><a href="zips/zip-0301.rst">Zcash Stratum Protocol</a></td> <td>Active</td>
<tr> <td>308</td> <td class="left"><a href="zips/zip-0308.rst">Sprout to Sapling Migration</a></td> <td>Active</td>
<tr> <td>316</td> <td class="left"><a href="zips/zip-0316.rst">Unified Addresses and Unified Viewing Keys</a></td> <td>[Revision 0] Active, [Revision 1] Withdrawn, [Revision 2] Draft</td>
<tr> <td>317</td> <td class="left"><a href="zips/zip-0317.rst">Proportional Transfer Fee Mechanism</a></td> <td>Active</td>
<tr> <td>317</td> <td class="left"><a href="zips/zip-0317.rst">Proportional Transfer Fee Mechanism</a></td> <td>[Revision 0] Active, [Revision 1: NU6.3] Draft, [Revision 2] Draft</td>
<tr> <td>320</td> <td class="left"><a href="zips/zip-0320.rst">Defining an Address Type to which funds can only be sent from Transparent Addresses</a></td> <td>Active</td>
<tr> <td>321</td> <td class="left"><a href="zips/zip-0321.rst">Payment Request URIs</a></td> <td>Active</td>
<tr> <td>401</td> <td class="left"><a href="zips/zip-0401.rst">Addressing Mempool Denial-of-Service</a></td> <td>Active</td>
Expand Down Expand Up @@ -358,7 +358,7 @@ Index of ZIPs
<tr> <td><span class="reserved">314</span></td> <td class="left"><a class="reserved" href="zips/zip-0314.rst">Privacy upgrades to the Zcash light client protocol</a></td> <td>Reserved</td>
<tr> <td>315</td> <td class="left"><a href="zips/zip-0315.rst">Best Practices for Wallet Implementations</a></td> <td>Draft</td>
<tr> <td>316</td> <td class="left"><a href="zips/zip-0316.rst">Unified Addresses and Unified Viewing Keys</a></td> <td>[Revision 0] Active, [Revision 1] Withdrawn, [Revision 2] Draft</td>
<tr> <td>317</td> <td class="left"><a href="zips/zip-0317.rst">Proportional Transfer Fee Mechanism</a></td> <td>Active</td>
<tr> <td>317</td> <td class="left"><a href="zips/zip-0317.rst">Proportional Transfer Fee Mechanism</a></td> <td>[Revision 0] Active, [Revision 1: NU6.3] Draft, [Revision 2] Draft</td>
<tr> <td><span class="reserved">319</span></td> <td class="left"><a class="reserved" href="zips/zip-0319.rst">Options for Shielded Pool Retirement</a></td> <td>Reserved</td>
<tr> <td>320</td> <td class="left"><a href="zips/zip-0320.rst">Defining an Address Type to which funds can only be sent from Transparent Addresses</a></td> <td>Active</td>
<tr> <td>321</td> <td class="left"><a href="zips/zip-0321.rst">Payment Request URIs</a></td> <td>Active</td>
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151 changes: 107 additions & 44 deletions zips/zip-0317.rst
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Expand Up @@ -8,10 +8,11 @@
Original-Authors: Aditya Bharadwaj
Credits: Madars Virza
Francisco Gindre
Status: Active
Status: [Revision 0] Active, [Revision 1: NU6.3] Draft, [Revision 2] Draft

@daira daira Jun 30, 2026

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Suggested change
Status: [Revision 0] Active, [Revision 1: NU6.3] Draft, [Revision 2] Draft
Status: [Revision 0] Active, [Revision 1: NU6.3] Proposed, [Revision 2] Draft

(subject to ZIP Editor consensus in the 2026-06-30 sync meeting)

Category: Standards / Wallet
Obsoletes: ZIP 313
Created: 2022-08-15
Last-Updated: 2026-06-26
License: MIT
Discussions-To: <https://forum.zcashcommunity.com/t/zip-proportional-output-fee-mechanism-pofm/42808>
Pull-Request: <https://github.com/zcash/zips/pull/631>
Expand Down Expand Up @@ -66,7 +67,7 @@ Requirements
============

* The conventional fee formula should not favour or discriminate against any
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of the Orchard, Sapling, or transparent protocols.
of the Ironwood, Orchard, Sapling, or transparent protocols.
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* The fee for a transaction should scale linearly with the number of inputs
and/or outputs.
* Users should not be penalised for sending transactions constructed
Expand All @@ -78,8 +79,6 @@ Requirements
* The conventional fee should not leak private information used in
constructing the transaction; that is, it should be computable from only
the public data of the transaction.
* Users should be discouraged from issuing new “garbage” Custom Assets.
The fee should reflect the cost of adding new data to the global state.


Specification
Expand All @@ -97,11 +96,44 @@ Let $\mathsf{max}(a, b)$ be the greater of $a$ and $b$. |br|
Let $\mathsf{floor}(x)$ be the largest integer $\leq x$. |br|
Let $\mathsf{ceiling}(x)$ be the smallest integer $\geq x$.

Revisions
---------

.. _`Revision 0`:

* Revision 0: The initial fee mechanism specified by this ZIP, in effect
prior to the Ironwood network upgrade.
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.. _`Revision 1`:

* Revision 1: Adds a contribution for Ironwood-pool [#zip-0229]_ Actions, to
be enacted at the Ironwood network upgrade (NU6.3 [#zip-0258]_).
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.. _`Revision 2`:

* Revision 2 (draft): Adds fee handling for memo bundles [#zip-0231]_, which
are defined as a modification to the Extensible Transaction Format
[#zip-0248]_. This revision is a draft, and depends on ZIP 248, which has
not yet been deployed.

Fee calculation
---------------

This specification defines several parameters that are used to calculate the
conventional fee:
Wallets implementing this specification SHOULD use a conventional fee,
calculated in zatoshis, of

|br|

.. math::

\mathit{conventional\_fee} = \mathit{marginal\_fee} \cdot \mathsf{max}(\mathit{grace\_actions},\, \mathit{logical\_actions})

|br|

where $\mathit{logical\_actions}$ is the sum of the contributions defined by
the applicable revision of this specification (see `Revisions`_). A
contribution defined by a given revision is also included in all later
revisions. This calculation uses the following parameters:

============================================== ============= ==============================================
Parameter Value Units
Expand All @@ -110,44 +142,26 @@ Parameter Value Units
:math:`\mathit{grace\_actions}` :math:`2` logical actions
:math:`\mathit{p2pkh\_standard\_input\_size}` :math:`150` bytes
:math:`\mathit{p2pkh\_standard\_output\_size}` :math:`34` bytes
:math:`\mathit{creation\_cost}` :math:`100` logical actions
============================================== ============= ==============================================

Wallets implementing this specification SHOULD use a conventional fee
calculated in zatoshis per the following formulae:
As of `Revision 0`_, the following contributions are defined:

|br|

.. math::

\begin{array}{lcl}
\mathit{free\_memo\_chunks} &=& \begin{cases}
2, &\!\!\textsf{if } \mathit{nOutputsSapling} + \mathit{nA\kern-0.05em ctionsOrchard} > 0, \\
0, &\!\!\textsf{otherwise}
\end{cases}
\\[4ex]
\mathit{contribution}_{\,\mathsf{Transparent}} &=& \mathsf{max}\big(\mathsf{ceiling}\big(\frac{\mathit{tx\_in\_total\_size}}{\mathit{p2pkh\_standard\_input\_size}}\big),\,
\mathsf{ceiling}\big(\frac{\mathit{tx\_out\_total\_size}}{\mathit{p2pkh\_standard\_output\_size}}\big)\big) \\
\mathit{contribution}_{\,\mathsf{Sprout}} &=& 2 \cdot \mathit{nJoinSplit} \\
\mathit{contribution}_{\,\mathsf{Sapling}} &=& \mathsf{max}(\mathit{nSpendsSapling},\, \mathit{nOutputsSapling}) \\
\mathit{contribution}_{\,\mathsf{Orchard}} &=& \mathit{nA\kern-0.1em ctionsOrchard} \\
\mathit{contribution}_{\,\mathsf{ZSAIssuance}} &=& \mathit{nZS\kern-0.1em AIssueNotes} \\
\mathit{contribution}_{\,\mathsf{ZSACreation}} &=& \mathit{creation\_cost} \cdot \mathit{nA\kern-0.1em ssetCreations} \\
\mathit{contribution}_{\,\mathsf{Memos}} &=& \mathsf{max}\big(0, \mathit{nMemoChunks} - \mathit{free\_memo\_chunks}\big) \\
\\
\mathit{logical\_actions} &=& \mathit{contribution}_{\,\mathsf{Transparent}} +
\mathit{contribution}_{\,\mathsf{Sprout}} +
\mathit{contribution}_{\,\mathsf{Sapling}} +
\mathit{contribution}_{\,\mathsf{Orchard}} \\
& & \hspace{1em} +\; \mathit{contribution}_{\,\mathsf{ZSAIssuance}} +
\mathit{contribution}_{\,\mathsf{ZSACreation}} +
\mathit{contribution}_{\,\mathsf{Memos}} \\
\\
\mathit{conventional\_fee} &=& \mathit{marginal\_fee} \cdot \mathsf{max}(\mathit{grace\_actions},\, \mathit{logical\_actions}) \\[6ex]
\mathit{contribution}_{\,\mathsf{Orchard}} &=& \mathit{nA\kern-0.1em ctionsOrchard}
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\end{array}

The inputs to this formula are taken from transaction fields defined in the Zcash protocol
specification [#protocol-txnencoding]_:
|br|

These contributions are computed from transaction fields defined in the Zcash
protocol specification [#protocol-txnencoding]_:

============================================= ====== ====================================================================
Input Units Description
Expand All @@ -158,8 +172,51 @@ Input Units Description
:math:`\mathit{nSpendsSapling}` number the number of Sapling spends
:math:`\mathit{nOutputsSapling}` number the number of Sapling outputs
:math:`\mathit{nA\kern-0.1em ctionsOrchard}` number the number of Orchard actions
:math:`\mathit{nZS\kern-0.1em AIssueNotes}` number the number of ``IssueNote`` outputs
:math:`\mathit{nA\kern-0.1em ssetCreations}` number the number of Custom Assets newly added to the Global Issuance State
============================================= ====== ====================================================================

As of `Revision 1`_, the $\mathit{logical\_actions}$ sum additionally includes
a contribution for Ironwood-pool [#zip-0229]_ Actions, which use the same
Action structure as Orchard-pool Actions:

|br|

.. math::

\mathit{contribution}_{\,\mathsf{Ironwood}} = \mathit{nA\kern-0.1em ctionsIronwood}
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|br|

This contribution is computed from one additional transaction field:

============================================= ====== ====================================================================
Input Units Description
============================================= ====== ====================================================================
:math:`\mathit{nA\kern-0.1em ctionsIronwood}` number the number of Ironwood actions
============================================= ====== ====================================================================

As of `Revision 2`_ (draft), the $\mathit{logical\_actions}$ sum additionally
includes a contribution for memo bundles [#zip-0231]_:

|br|

.. math::

\begin{array}{lcl}
\mathit{free\_memo\_chunks} &=& \begin{cases}
2, &\!\!\textsf{if } \mathit{nOutputsSapling} + \mathit{nA\kern-0.05em ctionsOrchard} + \mathit{nA\kern-0.05em ctionsIronwood} > 0, \\
0, &\!\!\textsf{otherwise}
\end{cases}
\\[4ex]
\mathit{contribution}_{\,\mathsf{Memos}} &=& \mathsf{max}\big(0, \mathit{nMemoChunks} - \mathit{free\_memo\_chunks}\big)
\end{array}

|br|

This contribution is computed from one additional transaction field:

============================================= ====== ====================================================================
Input Units Description
============================================= ====== ====================================================================
:math:`\mathit{nMemoChunks}` number the number of memo chunks
============================================= ====== ====================================================================

Expand All @@ -177,7 +234,7 @@ Rationale for logical actions

The intention is to make the fee paid for a transaction depend on its
impact on the network, without discriminating between different protocols
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(Orchard, Sapling, or transparent). The impact on the network depends on
(Ironwood, Orchard, Sapling, or transparent). The impact on the network depends on
the numbers of inputs and outputs.

A previous proposal used $\mathit{inputs} + \mathit{outputs}$ instead of logical actions.
Expand Down Expand Up @@ -279,15 +336,6 @@ described above) to the original conventional fee of 10000 zatoshis
specified in [#zip-0313]_, and imposes a non-trivial cost for
potential denial-of-service attacks.

**ZSA Creation Cost**

Every newly created Custom Asset adds a new row to the Global Issuance
State [#zip-0227-global-issuance-state]_ that full validators need to
track in perpetuity. Subsequent issuance, finalization, or burn of
existing Custom Assets only changes the values in the corresponding row.
Imposing a higher cost on Custom Asset creation events disincentivizes
the creation of "junk" assets.

**Memo Chunks**

Making the fee linear in the number of memo chunks has the following properties:
Expand Down Expand Up @@ -614,6 +662,19 @@ Kris Nuttycombe, Jack Grigg, Francisco Gindre, Greg Pfeil, Teor, and
Deirdre Connolly for reviews and suggested improvements.


Change History
==============

2026-06-26
----------

- Added a draft of Revision 1, which adds an Ironwood-pool Action
contribution, to be enacted at the Ironwood network upgrade (NU6.3).
- Introduced the revisions mechanism: recast the existing fee mechanism as
Revision 0, and moved the memo bundle fee handling into a draft Revision 2.
- Removed the ZSA issuance and asset-creation fee contributions (ZIP 227).


References
==========

Expand All @@ -622,7 +683,9 @@ References
.. [#protocol-txnencoding] `Zcash Protocol Specification, Version 2022.3.8. Section 7.1: Transaction Encoding and Consensus <protocol/protocol.pdf#txnencoding>`_
.. [#sigop-limit] `zcash/zips issue #568 - Document block transparent sigops limit consensus rule <https://github.com/zcash/zips/issues/568>`_
.. [#madars-1] `Madars concrete soft-fork proposal <https://forum.zcashcommunity.com/t/zip-reduce-default-shielded-transaction-fee-to-1000-zats/37566/89>`_
.. [#zip-0227-global-issuance-state] `ZIP 227: Issuance of Zcash Shielded Assets — Global Issuance State <zip-0227.rst#global-issuance-state>`_
.. [#zip-0231] `ZIP 231: Memo Bundles <zip-0231.rst>`_
.. [#zip-0229] `ZIP 229: Version 6 Transaction Format <zip-0229.md>`_
.. [#zip-0231] `ZIP 231: Memo Bundles <zip-0231.md>`_
.. [#zip-0248] `ZIP 248: Extensible Transaction Format (unmerged) <https://github.com/zcash/zips/pull/1156>`_
.. [#zip-0258] `ZIP 258: Deployment of the NU6.3 Network Upgrade <zip-0258.md>`_
.. [#zip-0313] `ZIP 313: Reduce Conventional Transaction Fee to 1000 zatoshis <zip-0313.rst>`_
.. [#zip-0401] `ZIP 401: Addressing Mempool Denial-of-Service <zip-0401.rst>`_
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