diff --git a/README.md b/README.md
index 916e912..fe7cfc7 100644
--- a/README.md
+++ b/README.md
@@ -67,7 +67,8 @@ How you can help! This library currently support about half the countries in the
 | Canada                 | CA   | SIN             | Person             | Person Identifier (Social Insurance Number)                                                                                            |
 | Cuba                   | CU   | NI              | Person             | Número de identidad, Cuban identity card numbers                                                                                       |
 | Cyprus                 | CY   | VAT             | Company            | Αριθμός Εγγραφής Φ.Π.Α. (Cypriot VAT number)                                                                                           |
-| Czech Republic         | CZ   | DIC             | Company            | Daňové identifikační číslo, Czech VAT number                                                                                           |
+| Czech Republic         | CZ   | DIC             | Vat                | Daňové identifikační číslo, Czech VAT number                                                                                           |
+| Czech Republic         | CZ   | ICO             | Company            | Identifikační číslo osoby, Czech Company Identification Number                                                                         |
 | Czech Republic         | CZ   | RC              | Person             | Rodné číslo, the Czech birth number                                                                                                    |
 | Swisserland            | CH   | SSN             | Person             | Swiss social security number ("Sozialversicherungsnummer")                                                                             |
 | Swisserland            | CH   | UID             | Company            | Unternehmens-Identifikationsnummer, Swiss business identifier                                                                          |
diff --git a/src/cz/ico.spec.ts b/src/cz/ico.spec.ts
new file mode 100644
index 0000000..4f318e6
--- /dev/null
+++ b/src/cz/ico.spec.ts
@@ -0,0 +1,64 @@
+import { validate, format } from './ico';
+import { InvalidLength, InvalidChecksum, InvalidComponent } from '../exceptions';
+
+describe('cz/ico', () => {
+  it('format:25596641', () => {
+    const result = format('25596641');
+
+    expect(result).toEqual('25596641');
+  });
+
+  it('validate:25596641 (Avast Software)', () => {
+    const result = validate('25596641');
+
+    expect(result.isValid && result.compact).toEqual('25596641');
+  });
+
+  it('validate:27082440 (Alza.cz)', () => {
+    const result = validate('27082440');
+
+    expect(result.isValid && result.compact).toEqual('27082440');
+  });
+
+  it('validate:45274649 (Škoda Auto)', () => {
+    const result = validate('45274649');
+
+    expect(result.isValid && result.compact).toEqual('45274649');
+  });
+
+  it('validate:00023205 (ČEZ)', () => {
+    const result = validate('00023205');
+
+    expect(result.isValid && result.compact).toEqual('00023205');
+  });
+
+  it('validate:00075370 (ČSÚ)', () => {
+    const result = validate('00075370');
+
+    expect(result.isValid && result.compact).toEqual('00075370');
+  });
+
+  it('validate:12345678 (invalid checksum)', () => {
+    const result = validate('12345678');
+
+    expect(result.error).toBeInstanceOf(InvalidChecksum);
+  });
+
+  it('validate:1234567 (too short)', () => {
+    const result = validate('1234567');
+
+    expect(result.error).toBeInstanceOf(InvalidLength);
+  });
+
+  it('validate:90000001 (reserved range)', () => {
+    const result = validate('90000001');
+
+    expect(result.error).toBeInstanceOf(InvalidComponent);
+  });
+
+  it('validate with spaces: 255 96 641', () => {
+    const result = validate('255 96 641');
+
+    expect(result.isValid && result.compact).toEqual('25596641');
+  });
+});
diff --git a/src/cz/ico.ts b/src/cz/ico.ts
new file mode 100644
index 0000000..d56112a
--- /dev/null
+++ b/src/cz/ico.ts
@@ -0,0 +1,81 @@
+/**
+ * IČO (Identifikační číslo osoby, Czech Company Identification Number).
+ *
+ * The IČO is an 8-digit identifier assigned to every business entity
+ * registered in the Czech Republic. It uses a weighted modulus-11 checksum.
+ *
+ * ENTITY
+ */
+
+import * as exceptions from '../exceptions';
+import { strings, weightedSum } from '../util';
+import { Validator, ValidateReturn } from '../types';
+
+function clean(input: string): ReturnType<typeof strings.cleanUnicode> {
+  return strings.cleanUnicode(input, ' -./');
+}
+
+function checksum(value: string): boolean {
+  const [front, check] = strings.splitAt(value, -1);
+
+  const sum = weightedSum(front, {
+    modulus: 11,
+    weights: [8, 7, 6, 5, 4, 3, 2, 1],
+  });
+
+  const v = (11 - sum) % 11;
+
+  return (v === 0 ? '1' : String(v % 10)) === check;
+}
+
+const impl: Validator = {
+  name: 'Czech Company Identification Number',
+  localName: 'Identifikační číslo osoby',
+  abbreviation: 'IČO',
+
+  compact(input: string): string {
+    const [value, err] = clean(input);
+
+    if (err) {
+      throw err;
+    }
+
+    return value;
+  },
+
+  format(input: string): string {
+    const [value] = clean(input);
+
+    return value;
+  },
+
+  validate(input: string): ValidateReturn {
+    const [value, error] = clean(input);
+
+    if (error) {
+      return { isValid: false, error };
+    }
+    if (value.length !== 8) {
+      return { isValid: false, error: new exceptions.InvalidLength() };
+    }
+    if (!strings.isdigits(value)) {
+      return { isValid: false, error: new exceptions.InvalidFormat() };
+    }
+    if (value.startsWith('9')) {
+      return { isValid: false, error: new exceptions.InvalidComponent() };
+    }
+    if (!checksum(value)) {
+      return { isValid: false, error: new exceptions.InvalidChecksum() };
+    }
+
+    return {
+      isValid: true,
+      compact: value,
+      isIndividual: false,
+      isCompany: true,
+    };
+  },
+};
+
+export const { name, localName, abbreviation, validate, format, compact } =
+  impl;
diff --git a/src/cz/index.ts b/src/cz/index.ts
index 274ce10..d386074 100644
--- a/src/cz/index.ts
+++ b/src/cz/index.ts
@@ -1,2 +1,3 @@
 export * as dic from './dic';
+export * as ico from './ico';
 export * as rc from './rc';