Fix Czechia to accept CZ prefix 🇨🇿

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 Fixes:
 - Fix Belgium to ignore `-` and `.` 🇧🇪
+- Fix Czechia to accept `CZ` prefix 🇨🇿
 
 ## [1.3.0] - 2025-12-12
 

lib/tin_valid/czechia_tin.rb

@@ -37,10 +37,12 @@ def valid? = valid_v1? || valid_v2?
     }x
     private_constant :MATCHER_V2
 
+    def normalized = @normalized ||= tin&.delete_prefix("CZ")
+
     def valid_v1?
-      match = MATCHER_V1.match(tin)
+      match = MATCHER_V1.match(normalized)
       return false unless match
-      return false if tin == "000000000"
+      return false if normalized == "000000000"
       return true if birth_date.nil?
       return false if year_of_birth >= 1954
 
@@ -55,9 +57,9 @@ def valid_v1?
     end
 
     def valid_v2?
-      match = MATCHER_V2.match(tin)
+      match = MATCHER_V2.match(normalized)
       return false unless match
-      return false if tin == "0000000000"
+      return false if normalized == "0000000000"
       return true if birth_date.nil?
       return false if year_of_birth < 1954
 

spec/tin_valid/czechia_tin_spec.rb

@@ -4,6 +4,7 @@
   describe "#valid?" do
     valid_values = [
       ["420901999", nil],
+      ["CZ420901999", nil],
       ["420901/999", nil],
       ["0009019999", nil],
       ["000901/9999", nil],