diff --git a/src/lib/isIdentityCard.js b/src/lib/isIdentityCard.js
index 7e20064e1..206bb3740 100644
--- a/src/lib/isIdentityCard.js
+++ b/src/lib/isIdentityCard.js
@@ -72,7 +72,7 @@ const validators = {
       return false;
     }
 
-    if (!str.match(/^\d{6}[\-A\+]\d{3}[0-9ABCDEFHJKLMNPRSTUVWXY]{1}$/)) {
+    if (!str.match(/^\d{6}[\-+A-FU-Y]\d{3}[0-9ABCDEFHJKLMNPRSTUVWXY]{1}$/)) {
       return false;
     }
 
diff --git a/src/lib/isTaxID.js b/src/lib/isTaxID.js
index 2c293f71a..67b53f305 100644
--- a/src/lib/isTaxID.js
+++ b/src/lib/isTaxID.js
@@ -501,12 +501,17 @@ function etEeCheck(tin) {
 function fiFiCheck(tin) {
   // Extract year and add century
   let full_year = tin.slice(4, 6);
-  const century_symbol = tin.slice(6, 7);
+  const century_symbol = tin.slice(6, 7).toUpperCase();
   switch (century_symbol) {
     case '+':
       full_year = `18${full_year}`;
       break;
     case '-':
+    case 'U':
+    case 'V':
+    case 'W':
+    case 'X':
+    case 'Y':
       full_year = `19${full_year}`;
       break;
     default:
@@ -1198,7 +1203,7 @@ const taxIdFormat = {
   'es-AR': /(20|23|24|27|30|33|34)[0-9]{8}[0-9]/,
   'es-ES': /^(\d{0,8}|[XYZKLM]\d{7})[A-HJ-NP-TV-Z]$/i,
   'et-EE': /^[1-6]\d{6}(00[1-9]|0[1-9][0-9]|[1-6][0-9]{2}|70[0-9]|710)\d$/,
-  'fi-FI': /^\d{6}[-+A]\d{3}[0-9A-FHJ-NPR-Y]$/i,
+  'fi-FI': /^\d{6}[-+A-FU-Y]\d{3}[0-9A-FHJ-NPR-Y]$/i,
   'fr-BE': /^\d{11}$/,
   'fr-FR': /^[0-3]\d{12}$|^[0-3]\d\s\d{2}(\s\d{3}){3}$/, // Conforms both to official spec and provided example
   'fr-LU': /^\d{13}$/,
diff --git a/test/validators.test.js b/test/validators.test.js
index 98d2a12ff..cdb36603e 100644
--- a/test/validators.test.js
+++ b/test/validators.test.js
@@ -6834,11 +6834,14 @@ describe('Validators', () => {
           '131052A308T', // People born in 2000s
           '131052+308T', // People born in 1800s
           '131052-313Y',
+          '010594Y9021', // New century signs since 2023
+          '020502E902X',
         ],
         invalid: [
           '131052308T',
           '131052-308T ',
           '131052-308A',
+          '131052G308T',
         ],
       },
       {
@@ -13982,13 +13985,17 @@ describe('Validators', () => {
       valid: [
         '131052-308T',
         '131002+308W',
-        '131019A3089'],
+        '131019A3089',
+        '010594Y9021',
+        '020502E902X',
+        '290200A1239'],
       invalid: [
         '131052308T',
         '131052-308TT',
         '131052S308T',
         '13 1052-308/T',
-        '290219A1111'],
+        '290219A1111',
+        '290200Y1239'],
     });
     test({
       validator: 'isTaxID',