Fix Sweden TINs versions with 4-digit years 🇸🇪

CHANGELOG.md

@@ -3,6 +3,7 @@
 Fixes:
 - Fix Belgium to ignore `-` and `.` 🇧🇪
 - Fix Czechia to accept `CZ` prefix 🇨🇿
+- Fix Sweden TINs versions with 4-digit years 🇸🇪
 
 ## [1.3.0] - 2025-12-12
 

lib/tin_valid/sweden_tin.rb

@@ -21,8 +21,7 @@ def valid?
         day = match[:day]
         next false unless date_valid?(year, month, day)
 
-        id = match[:id]
-        match[:check].to_i == checksum("#{year[..2]}#{month}#{day}#{id}")
+        check_match?(year:, month:, day:, id: match[:id], check: match[:check])
       end
     end
 
@@ -70,6 +69,11 @@ def valid?
     ].freeze
     private_constant :VERSIONS
 
+    def check_match?(year:, month:, day:, id:, check:)
+      checkyear = year.size == 4 ? year[2..] : year
+      check.to_i == checksum("#{checkyear}#{month}#{day}#{id}")
+    end
+
     def checksum(numbers)
       # 1. Multiply the values of each position by the corresponding weight:
       # - C1: 2

spec/tin_valid/sweden_tin_spec.rb

@@ -4,6 +4,8 @@
   describe "#valid?" do
     valid_values = [
       ["640883-3231", nil],
+      ["199109141086", nil],
+      ["040731-1372", nil],
       ["640823-3234", nil],
       ["640823-3234", Date.new(1964, 8, 23)],
     ]