diff --git a/changelog.d/766-trade-cli-subprocess-timeout.fixed.md b/changelog.d/766-trade-cli-subprocess-timeout.fixed.md
new file mode 100644
index 00000000..b647f298
--- /dev/null
+++ b/changelog.d/766-trade-cli-subprocess-timeout.fixed.md
@@ -0,0 +1,3 @@
+Give the synthetic import-entry CLI tests a subprocess budget that covers the
+rules-engine import their CLI pays before doing any work, so they stop timing
+out on contended runners.
diff --git a/packages/microcosm-build/tests/test_us_trade_entries_cli.py b/packages/microcosm-build/tests/test_us_trade_entries_cli.py
index b2310c3e..d34f0252 100644
--- a/packages/microcosm-build/tests/test_us_trade_entries_cli.py
+++ b/packages/microcosm-build/tests/test_us_trade_entries_cli.py
@@ -30,6 +30,18 @@
 
 GOLDEN = Path(__file__).parent / "golden" / "us_trade"
 CLI = Path(__file__).resolve().parents[3] / "tools" / "build_us_import_entries.py"
+
+# Every spawn of the CLI pays its import chain before doing any work, and that
+# chain is dominated by machinery the trade code never uses: importing
+# `us_runtime.us_trade.*` executes `us_runtime/__init__`, which pulls in
+# spine_agreement and, through it, the whole policyengine-us system. Measured
+# on the same fixture as `test_cli_fails_when_margins_missing_from_window`
+# (a CLI that only reads a 2-row parquet and exits 1): 35.9 s with the engine
+# installed, 5.4 s without. That import is parameter-tree I/O, so it stretches
+# with runner disk contention — at the old 300 s this test timed out on main
+# (run 32910539480) after passing on the PR. The headroom belongs here until
+# the import is made lazy; see the note on the PR that raised this.
+CLI_TIMEOUT_SECONDS = 900
 CONTRACT = GOLDEN / "engine_entry_contract.json"
 
 
@@ -94,7 +106,7 @@ def _run(margins_dir: Path, out_dir: Path, start: str = "2026-01"):
         capture_output=True,
         text=True,
         check=False,
-        timeout=300,
+        timeout=CLI_TIMEOUT_SECONDS,
     )
 
 
@@ -346,7 +358,7 @@ def test_override_build_registers_override_basis(tmp_path):
         capture_output=True,
         text=True,
         check=False,
-        timeout=300,
+        timeout=CLI_TIMEOUT_SECONDS,
     )
     assert result.returncode == 0, result.stderr
     register = json.loads((out_dir / "assumptions.json").read_text())
diff --git a/packages/microcosm-build/tests/test_us_trade_imdb_bulk.py b/packages/microcosm-build/tests/test_us_trade_imdb_bulk.py
index 8ca0b5c6..5cba02df 100644
--- a/packages/microcosm-build/tests/test_us_trade_imdb_bulk.py
+++ b/packages/microcosm-build/tests/test_us_trade_imdb_bulk.py
@@ -38,6 +38,13 @@
 REPO_ROOT = Path(__file__).resolve().parents[3]
 BUILD_CLI = REPO_ROOT / "tools" / "build_us_import_entry_margins.py"
 
+# Same import tax as test_us_trade_entries_cli: importing `us_runtime.us_trade.*`
+# executes `us_runtime/__init__`, which drags in spine_agreement and the whole
+# policyengine-us system before this CLI does any work — measured at 33.0 s of
+# import in the engine lane. The lightweight `-c` spawns below keep their 60 s
+# budget; only the full-CLI spawns pay this.
+CLI_TIMEOUT_SECONDS = 900
+
 
 def _field(line: list[str], start: int, end: int, value: str, *, align: str) -> None:
     """Place ``value`` into the 1-indexed inclusive [start, end] span."""
@@ -822,7 +829,7 @@ def test_build_cli_end_to_end_offline(tmp_path):
         ],
         capture_output=True,
         text=True,
-        timeout=300,
+        timeout=CLI_TIMEOUT_SECONDS,
     )
     assert result.returncode == 0, result.stderr
     report = json.loads((out_dir / "build_report.json").read_text())
@@ -905,7 +912,7 @@ def test_build_cli_failure_leaves_prior_publication_untouched(tmp_path):
         ],
         capture_output=True,
         text=True,
-        timeout=300,
+        timeout=CLI_TIMEOUT_SECONDS,
     )
     assert result.returncode == 1
     assert "nothing was published" in result.stderr
@@ -963,7 +970,7 @@ def test_build_cli_success_replaces_prior_publication_completely(tmp_path):
         ],
         capture_output=True,
         text=True,
-        timeout=300,
+        timeout=CLI_TIMEOUT_SECONDS,
     )
     assert result.returncode == 0, result.stderr
     assert not stale.exists()
@@ -998,7 +1005,7 @@ def test_build_cli_fails_on_control_mismatch(tmp_path):
         ],
         capture_output=True,
         text=True,
-        timeout=300,
+        timeout=CLI_TIMEOUT_SECONDS,
     )
     assert result.returncode == 1
     assert "RECONCILIATION FAIL" in result.stderr