diff --git a/docs/advanced_features/nsa_prefill_cp_index_skip_cache_communication_plan.md b/docs/advanced_features/nsa_prefill_cp_index_skip_cache_communication_plan.md
index 48ff09622..8cf48772f 100644
--- a/docs/advanced_features/nsa_prefill_cp_index_skip_cache_communication_plan.md
+++ b/docs/advanced_features/nsa_prefill_cp_index_skip_cache_communication_plan.md
@@ -1135,6 +1135,7 @@ Completion criteria:
   - Test-only/legacy host stubs without compact metadata keep dense-slot behavior; real compact host pools still fail fast if an inactive logical index layer is requested.
   - Direct HiCache tests now follow the production CPU-index contract before calling TAI `cudaMemcpyBatchAsync` paths.
   - Host-register allocation now checks `cudaHostRegister` errors and unregisters host tensors on object finalization; this prevents repeated CUDA unit tests from poisoning later CUDA ops with stale `cudaErrorHostMemoryAlreadyRegistered`.
+  - Follow-up correction: target+draft shared `--hicache-size` budgeting must also use active index-layer count in `_estimate_hicache_size_per_token`; otherwise the host/L2 buffer is physically compact but the L2 token capacity remains conservatively sized as if all target layers still had index cache.
   - Verification: remote container P3-P6 suite passed:
     `test_nsa_pool_host_unit.py`, `test_model_runner_kv_cache_mixin.py`,
     `test_cp_shared_kv_transfer_mapping.py`, `test_pd_state_layer_ids.py`,
diff --git a/python/sglang/srt/mem_cache/hiradix_cache.py b/python/sglang/srt/mem_cache/hiradix_cache.py
index 7c6e30450..0ca4a4cb4 100644
--- a/python/sglang/srt/mem_cache/hiradix_cache.py
+++ b/python/sglang/srt/mem_cache/hiradix_cache.py
@@ -75,10 +75,17 @@ def _estimate_hicache_size_per_token(kv_cache) -> int:
             kv_cache.index_head_dim
             + kv_cache.index_head_dim // kv_cache.quant_block_size * 4
         )
+        index_layer_count = len(
+            getattr(
+                kv_cache,
+                "index_active_layer_ids",
+                range(kv_cache.layer_num),
+            )
+        )
         return (
             kv_cache.kv_cache_dim * dtype_size * kv_cache.layer_num
             + indexer_size_per_token
-            * kv_cache.layer_num
+            * index_layer_count
             * NSATokenToKVPool.index_k_with_scale_buffer_dtype.itemsize
         )
     if isinstance(kv_cache, MLATokenToKVPool):
diff --git a/test/registered/unit/mem_cache/test_cp_hicache_metadata.py b/test/registered/unit/mem_cache/test_cp_hicache_metadata.py
index 3301f744f..b0ed171ae 100644
--- a/test/registered/unit/mem_cache/test_cp_hicache_metadata.py
+++ b/test/registered/unit/mem_cache/test_cp_hicache_metadata.py
@@ -209,6 +209,23 @@ class TestHiRadixCacheCPDraftHostPool(CustomTestCase):
         # the paged index buffer: 128 uint8 K bytes + 4 uint8 scale bytes.
         self.assertEqual(size_per_token, (656 + 128 + 4) * 78)
 
+    def test_fp8_nsa_hicache_size_estimate_uses_active_index_layers(self):
+        pool = object.__new__(NSATokenToKVPool)
+        pool.store_dtype = torch.uint8
+        pool.kv_cache_dim = 656
+        pool.layer_num = 78
+        pool.index_head_dim = 128
+        pool.quant_block_size = 128
+        pool.index_active_layer_ids = tuple(range(0, 78, 4))
+
+        size_per_token = hiradix_cache._estimate_hicache_size_per_token(pool)
+
+        indexer_size_per_token = 128 + 4
+        self.assertEqual(
+            size_per_token,
+            656 * 78 + indexer_size_per_token * len(pool.index_active_layer_ids),
+        )
+
     def test_fp8_shared_budget_matches_target_and_one_layer_draft_capacity(self):
         bytes_per_layer = 656 + 128 + 4
         target_size_per_token = bytes_per_layer * 78