diff --git a/nexa_coa_setup/hooks.py b/nexa_coa_setup/hooks.py
index babbb238..59fbcd13 100644
--- a/nexa_coa_setup/hooks.py
+++ b/nexa_coa_setup/hooks.py
@@ -79,10 +79,52 @@ def post_init_hook(env):
     _normalize_company_hst_number(env)
     _archive_unused_l10n_ca_accounts(env)
     _rename_legacy_accounts(env)
+    _archive_unused_taxes(env)
     _lock_fiscal_year_2025(env)
     _logger.info("nexa_coa_setup: post_init_hook complete")
 
 
+# Tax names to keep ACTIVE (covers GST/HST/QST/PST across provinces + zero-rated
+# export + exempt). Everything else gets archived if it has zero usage on
+# existing journal entries.
+_KEEP_TAX_NAMES = {
+    "5% GST", "13% HST", "14% HST", "15% HST",
+    "11% GST+PST SK", "12% GST+PST BC", "12% GST+PST MB", "14.975% GST+QST",
+    "9.975% QST", "7% PST BC", "8% PST MB", "6% PST SK", "5% PST SK",
+    "0% GST", "0% Exempt", "0% Int",
+}
+
+
+def _archive_unused_taxes(env):
+    """Archive active taxes whose name is NOT in _KEEP_TAX_NAMES AND that
+    have no usage on existing move lines. Preserves audit trail for historical
+    moves; just hides duplicates and unused defaults from the active set.
+    """
+    keep_names = list(_KEEP_TAX_NAMES)
+    env.cr.execute(
+        """
+        SELECT t.id
+        FROM account_tax t
+        WHERE t.active = true
+          AND COALESCE(t.name->>'en_US', '') != ALL(%s)
+          AND NOT EXISTS (
+              SELECT 1 FROM account_move_line_account_tax_rel r
+              WHERE r.account_tax_id = t.id
+          )
+        """,
+        (keep_names,),
+    )
+    ids = [r[0] for r in env.cr.fetchall()]
+    if not ids:
+        _logger.info("nexa_coa_setup: no unused taxes to archive")
+        return
+    env["account.tax"].browse(ids).write({"active": False})
+    _logger.info(
+        "nexa_coa_setup: archived %d unused taxes (kept set: %d names)",
+        len(ids), len(keep_names),
+    )
+
+
 def _normalize_company_hst_number(env):
     """Convert '741224877' to '741224877 RT0001' if not already in full form."""
     company = env.ref("base.main_company", raise_if_not_found=False)