diff --git a/plans/plans.go b/plans/plans.go
index 68b3365..b0f0d8b 100644
--- a/plans/plans.go
+++ b/plans/plans.go
@@ -472,13 +472,13 @@ plans:
       custom_domains: false
       sla: false
   # hobby_yearly mirrors hobby exactly — same limits + features. Only the
-  # billing period and price differ ($90/yr ≈ $7.50/mo, ~17% off vs $9 x 12).
+  # billing period and price differ ($97.20/yr ≈ $8.10/mo, 10% off vs $9 x 12).
   # The webhook upgrades teams to the "hobby" tier regardless of which
   # cycle the user paid on; this variant exists only so the checkout
   # handler can pick the right Razorpay plan_id at subscribe time.
   hobby_yearly:
     display_name: "Hobby (yearly)"
-    price_monthly_cents: 9000
+    price_monthly_cents: 9720
     billing_period: "yearly"
     trial_days: 14
     limits:
@@ -525,10 +525,10 @@ plans:
       alerts: true
       custom_domains: true
       sla: false
-  # pro_yearly mirrors pro exactly. $490/yr ≈ $40.83/mo (~17% off $49 x 12).
+  # pro_yearly mirrors pro exactly. $529.20/yr ≈ $44.10/mo (10% off $49 x 12).
   pro_yearly:
     display_name: "Pro (yearly)"
-    price_monthly_cents: 49000
+    price_monthly_cents: 52920
     billing_period: "yearly"
     trial_days: 0
     limits:
@@ -575,10 +575,10 @@ plans:
       alerts: true
       custom_domains: true
       sla: true
-  # team_yearly mirrors team exactly. $1990/yr ≈ $165.83/mo (~17% off $199 x 12).
+  # team_yearly mirrors team exactly. $2149.20/yr ≈ $179.10/mo (10% off $199 x 12).
   team_yearly:
     display_name: "Team (yearly)"
-    price_monthly_cents: 199000
+    price_monthly_cents: 214920
     billing_period: "yearly"
     trial_days: 0
     limits:
diff --git a/plans/plans_test.go b/plans/plans_test.go
index 24adbab..a19cd57 100644
--- a/plans/plans_test.go
+++ b/plans/plans_test.go
@@ -177,6 +177,25 @@ func TestYearlyPrices_DiscountedVsMonthlyTimesTwelve(t *testing.T) {
 	}
 }
 
+// TestYearlyDiscountIsExactly10Percent locks the yearly-discount contract:
+// (yearly / 12) / monthly must equal 0.9 within a small tolerance for each
+// of hobby/pro/team. Future price changes that accidentally drift the
+// discount (e.g. forgetting to re-derive the yearly cents from the new
+// monthly) will fail this test.
+func TestYearlyDiscountIsExactly10Percent(t *testing.T) {
+	r := plans.Default()
+	const tolerance = 0.01
+	for _, base := range []string{"hobby", "pro", "team"} {
+		monthly := float64(r.Get(base).PriceMonthly)
+		yearly := float64(r.Get(base + "_yearly").PriceMonthly)
+		require.Greater(t, monthly, 0.0, "%s monthly price must be > 0", base)
+		ratio := (yearly / 12.0) / monthly
+		assert.InDelta(t, 0.9, ratio, tolerance,
+			"%s_yearly effective monthly / %s monthly must be 0.9 (10%% off); got %.4f (yearly=%d, monthly=%d)",
+			base, base, ratio, int(yearly), int(monthly))
+	}
+}
+
 func TestValidatePromotion_ValidCode_ReturnsPromotion(t *testing.T) {
 	yaml := `
 plans: