diff --git a/zips/zip-0235.md b/zips/zip-0235.md
index df8b840ea..4fd55f977 100644
--- a/zips/zip-0235.md
+++ b/zips/zip-0235.md
@@ -142,6 +142,25 @@ a year.
 If 60% of these fees are removed from circulation, that would be 210.864 ZEC per
 year. [^zsf-fee-estimator]
 
+## Rationale for the 60/40 split
+
+An asymmetric fee split favoring the removal mechanism is preferred for two
+reasons. [^nsm-incentives]
+
+1. An equal split, or a split that favors miners, creates a long-term security
+concern. As issuance approaches zero, the proportion of fee revenue that a
+miner can recoup through future block subsidies depends on their share of
+network hash rate. Miners would face an incentive to roll back a preceding
+block whenever the fee difference between adjacent blocks exceeds their
+mining costs plus current issuance. By directing a larger share (60%) to the
+removal mechanism and a smaller share (40%) to miners, the block-to-block
+fee variation visible to miners is reduced, narrowing the window in which
+rollback attacks are profitable.
+2. An asymmetric split aids implementation correctness. Equal fractions
+make it impossible to detect certain classes of bugs, such as swapping
+the miner and removal fractions, or swapping the consensus checks on those
+amounts. Any split other than 50/50 makes such errors observable in testing.
+
 ## Considerations for the Future
 
 If transaction fees were to increase, further modifications can easily be
@@ -192,4 +211,6 @@ ZIP 233 ("NSM: Removing Funds From Circulation" [^zip-0233]).
 
 [^zsf-fee-estimator]: [GitHub repository eigerco/zsf-fee-estimator](https://github.com/eigerco/zsf-fee-estimator)
 
+[^nsm-incentives]: [Zcash Community Forum — Network Sustainability Mechanism (NSM), post by teor](https://forum.zcashcommunity.com/t/network-sustainability-mechanism-nsm/42703/104)
+
 [^eip-1559]: [EIP-1559: Fee market change for ETH 1.0 chain](https://eips.ethereum.org/EIPS/eip-1559)