diff --git a/CHANGELOG.md b/CHANGELOG.md
index f8a2390f5..4c505c134 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/) and this p
 
 - `net`: added `SandboxAuthorities` (defaulting to `lookup.sandbox.gobl.org`)
   and `WithSandbox`. Sandbox and live trust lists remain separate.
+- `sk`: Slovakia tax regime with VAT categories for standard (23%), reduced (19%) and super-reduced (5%) rates per zákon č. 222/2004 Z. z. § 27, EUR currency, `Europe/Bratislava` timezone, and IČ DPH tax identity validation (10 digits, modulo-11 check).
 
 ### Changed
 
diff --git a/data/regimes/sk.json b/data/regimes/sk.json
new file mode 100644
index 000000000..11c39146d
--- /dev/null
+++ b/data/regimes/sk.json
@@ -0,0 +1,197 @@
+{
+  "$schema": "https://gobl.org/draft-0/tax/regime-def",
+  "name": {
+    "en": "Slovakia",
+    "sk": "Slovensko"
+  },
+  "description": {
+    "en": "Slovakia's tax system is administered by the Financial Administration of the\nSlovak Republic (Finančná správa Slovenskej republiky). As an EU member state,\nSlovakia follows the EU VAT Directive.\n\nVAT (daň z pridanej hodnoty, DPH) applies at a standard rate, with reduced rates\nfor certain goods and services such as foodstuffs, medicines, medical devices,\nbooks, and accommodation. Exports and intra-EU supplies to VAT-registered buyers\nare zero-rated.\n\nBusinesses registered for VAT are identified by their IČ DPH, formed by the\nprefix SK followed by ten digits (e.g. SK2020273893)."
+  },
+  "sources": [
+    {
+      "title": {
+        "en": "Finančná správa - Daň z pridanej hodnoty (VAT)"
+      },
+      "url": "https://www.financnasprava.sk/sk/podnikatelia/dane/dan-z-pridanej-hodnoty",
+      "at": "2026-08-06T00:00:00"
+    },
+    {
+      "title": {
+        "en": "Slov-Lex - Zákon č. 222/2004 Z. z. o dani z pridanej hodnoty"
+      },
+      "url": "https://www.slov-lex.sk/ezbierky/pravne-predpisy/SK/ZZ/2004/222/",
+      "at": "2026-08-06T00:00:00"
+    },
+    {
+      "title": {
+        "en": "Financial Administration of the Slovak Republic (English)"
+      },
+      "url": "https://www.financnasprava.sk/en/",
+      "at": "2026-08-06T00:00:00"
+    }
+  ],
+  "time_zone": "Europe/Bratislava",
+  "country": "SK",
+  "currency": "EUR",
+  "tax_scheme": "VAT",
+  "scenarios": [
+    {
+      "schema": "bill/invoice",
+      "list": [
+        {
+          "tags": [
+            "reverse-charge"
+          ],
+          "cat": [
+            "VAT"
+          ],
+          "note": {
+            "cat": "VAT",
+            "key": "reverse-charge",
+            "text": "Reverse charge: Customer to account for VAT to the relevant tax authority."
+          }
+        }
+      ]
+    }
+  ],
+  "categories": [
+    {
+      "code": "VAT",
+      "name": {
+        "en": "VAT",
+        "sk": "DPH"
+      },
+      "title": {
+        "en": "Value Added Tax",
+        "sk": "Daň z pridanej hodnoty"
+      },
+      "keys": [
+        {
+          "key": "standard",
+          "name": {
+            "en": "Standard"
+          }
+        },
+        {
+          "key": "zero",
+          "name": {
+            "en": "Zero"
+          }
+        },
+        {
+          "key": "reverse-charge",
+          "name": {
+            "en": "Reverse charge"
+          },
+          "no_percent": true
+        },
+        {
+          "key": "exempt",
+          "name": {
+            "en": "Exempt"
+          },
+          "no_percent": true
+        },
+        {
+          "key": "export",
+          "name": {
+            "en": "Export"
+          },
+          "no_percent": true
+        },
+        {
+          "key": "intra-community",
+          "name": {
+            "en": "Intra-community"
+          },
+          "no_percent": true
+        },
+        {
+          "key": "outside-scope",
+          "name": {
+            "en": "Outside scope"
+          },
+          "no_percent": true
+        }
+      ],
+      "rates": [
+        {
+          "rate": "general",
+          "keys": [
+            "standard"
+          ],
+          "name": {
+            "en": "Standard Rate",
+            "sk": "Základná sadzba"
+          },
+          "values": [
+            {
+              "since": "2025-01-01",
+              "percent": "23.0%"
+            },
+            {
+              "since": "2011-01-01",
+              "percent": "20.0%"
+            }
+          ]
+        },
+        {
+          "rate": "reduced",
+          "keys": [
+            "standard"
+          ],
+          "name": {
+            "en": "Reduced Rate",
+            "sk": "Znížená sadzba"
+          },
+          "desc": {
+            "en": "Non-basic foodstuffs, electricity and certain catering services.",
+            "sk": "Potraviny okrem základných, elektrina a niektoré reštauračné služby."
+          },
+          "values": [
+            {
+              "since": "2025-01-01",
+              "percent": "19.0%"
+            }
+          ]
+        },
+        {
+          "rate": "super-reduced",
+          "keys": [
+            "standard"
+          ],
+          "name": {
+            "en": "Super-reduced Rate",
+            "sk": "Druhá znížená sadzba"
+          },
+          "desc": {
+            "en": "Basic foodstuffs, medicines, medical devices, books, and accommodation.",
+            "sk": "Základné potraviny, lieky, zdravotnícke pomôcky, knihy a ubytovanie."
+          },
+          "values": [
+            {
+              "since": "2025-01-01",
+              "percent": "5.0%"
+            }
+          ]
+        }
+      ],
+      "sources": [
+        {
+          "title": {
+            "en": "Slov-Lex - Zákon č. 222/2004 Z. z. § 27 (Sadzba dane)"
+          },
+          "url": "https://www.slov-lex.sk/ezbierky/pravne-predpisy/SK/ZZ/2004/222/",
+          "at": "2026-08-06T00:00:00"
+        },
+        {
+          "title": {
+            "en": "Slov-Lex - Zákon č. 490/2010 Z. z. (novela zákona č. 222/2004 Z. z.)"
+          },
+          "url": "https://www.slov-lex.sk/ezbierky/pravne-predpisy/SK/ZZ/2010/490/",
+          "at": "2026-08-06T00:00:00"
+        }
+      ]
+    }
+  ]
+}
\ No newline at end of file
diff --git a/data/rules/sk.json b/data/rules/sk.json
new file mode 100644
index 000000000..221a1a5c4
--- /dev/null
+++ b/data/rules/sk.json
@@ -0,0 +1,42 @@
+{
+  "id": "GOBL-SK",
+  "package": "sk",
+  "subsets": [
+    {
+      "id": "GOBL-SK-TAX-IDENTITY",
+      "object": "tax.Identity",
+      "subsets": [
+        {
+          "guard": "code in [SK]",
+          "subsets": [
+            {
+              "field": "code",
+              "subsets": [
+                {
+                  "guard": "present",
+                  "assert": [
+                    {
+                      "id": "GOBL-SK-TAX-IDENTITY-01",
+                      "desc": "tax identity code for SK must be 10 digits starting with 1-9",
+                      "tests": "matches ^[1-9]\\d{9}$"
+                    }
+                  ]
+                },
+                {
+                  "guard": "present",
+                  "assert": [
+                    {
+                      "id": "GOBL-SK-TAX-IDENTITY-02",
+                      "desc": "tax identity code for SK failed the checksum: the 10 digit number must be divisible by 11",
+                      "tests": "checksum"
+                    }
+                  ]
+                }
+              ]
+            }
+          ]
+        }
+      ]
+    }
+  ]
+}
diff --git a/data/schemas/tax/regime-code.json b/data/schemas/tax/regime-code.json
index 585a84591..707c6e08b 100644
--- a/data/schemas/tax/regime-code.json
+++ b/data/schemas/tax/regime-code.json
@@ -109,6 +109,10 @@
           "const": "SG",
           "title": "Singapore"
         },
+        {
+          "const": "SK",
+          "title": "Slovakia"
+        },
         {
           "const": "US",
           "title": "United States of America"
diff --git a/examples/sk/invoice-sk-sk.yaml b/examples/sk/invoice-sk-sk.yaml
new file mode 100644
index 000000000..593f70859
--- /dev/null
+++ b/examples/sk/invoice-sk-sk.yaml
@@ -0,0 +1,55 @@
+$schema: "https://gobl.org/draft-0/bill/invoice"
+uuid: "b3d5f7a1-2c4e-4b6a-8d9f-1a2b3c4d5e6f"
+series: "SAMPLE"
+code: "001"
+issue_date: "2025-03-01"
+
+supplier:
+  name: "Vzorová s.r.o."
+  tax_id:
+    country: "SK"
+    code: "2020273893"
+  addresses:
+    - num: "12"
+      street: "Hlavná"
+      locality: "Bratislava"
+      code: "81101"
+      country: "SK"
+  emails:
+    - addr: "fakturacia@example.sk"
+
+customer:
+  name: "Zákazník s.r.o."
+  tax_id:
+    country: "SK"
+    code: "7120001713"
+  addresses:
+    - num: "5"
+      street: "Štúrova"
+      locality: "Košice"
+      code: "04001"
+      country: "SK"
+
+lines:
+  - quantity: "10"
+    item:
+      name: "Softvérové služby"
+      price: "120.00"
+      unit: "h"
+    taxes:
+      - cat: VAT
+        rate: "standard"
+  - quantity: "100"
+    item:
+      name: "Elektrina"
+      price: "0.25"
+    taxes:
+      - cat: VAT
+        rate: "reduced"
+  - quantity: "5"
+    item:
+      name: "Knihy"
+      price: "20.00"
+    taxes:
+      - cat: VAT
+        rate: "super-reduced"
diff --git a/examples/sk/out/invoice-sk-sk.json b/examples/sk/out/invoice-sk-sk.json
new file mode 100644
index 000000000..e5ad39d72
--- /dev/null
+++ b/examples/sk/out/invoice-sk-sk.json
@@ -0,0 +1,150 @@
+{
+	"$schema": "https://gobl.org/draft-0/envelope",
+	"head": {
+		"uuid": "8a51fd30-2a27-11ee-be56-0242ac120002",
+		"dig": {
+			"alg": "sha256",
+			"val": "2e59c41a0a403e18ea546660126c31142267955460446e819c662c1ca539272e"
+		}
+	},
+	"doc": {
+		"$schema": "https://gobl.org/draft-0/bill/invoice",
+		"$regime": "SK",
+		"uuid": "b3d5f7a1-2c4e-4b6a-8d9f-1a2b3c4d5e6f",
+		"type": "standard",
+		"series": "SAMPLE",
+		"code": "001",
+		"issue_date": "2025-03-01",
+		"currency": "EUR",
+		"supplier": {
+			"name": "Vzorová s.r.o.",
+			"tax_id": {
+				"country": "SK",
+				"code": "2020273893"
+			},
+			"addresses": [
+				{
+					"num": "12",
+					"street": "Hlavná",
+					"locality": "Bratislava",
+					"code": "81101",
+					"country": "SK"
+				}
+			],
+			"emails": [
+				{
+					"addr": "fakturacia@example.sk"
+				}
+			]
+		},
+		"customer": {
+			"name": "Zákazník s.r.o.",
+			"tax_id": {
+				"country": "SK",
+				"code": "7120001713"
+			},
+			"addresses": [
+				{
+					"num": "5",
+					"street": "Štúrova",
+					"locality": "Košice",
+					"code": "04001",
+					"country": "SK"
+				}
+			]
+		},
+		"lines": [
+			{
+				"i": 1,
+				"quantity": "10",
+				"item": {
+					"name": "Softvérové služby",
+					"price": "120.00",
+					"unit": "h"
+				},
+				"sum": "1200.00",
+				"taxes": [
+					{
+						"cat": "VAT",
+						"key": "standard",
+						"rate": "general",
+						"percent": "23.0%"
+					}
+				],
+				"total": "1200.00"
+			},
+			{
+				"i": 2,
+				"quantity": "100",
+				"item": {
+					"name": "Elektrina",
+					"price": "0.25"
+				},
+				"sum": "25.00",
+				"taxes": [
+					{
+						"cat": "VAT",
+						"key": "standard",
+						"rate": "reduced",
+						"percent": "19.0%"
+					}
+				],
+				"total": "25.00"
+			},
+			{
+				"i": 3,
+				"quantity": "5",
+				"item": {
+					"name": "Knihy",
+					"price": "20.00"
+				},
+				"sum": "100.00",
+				"taxes": [
+					{
+						"cat": "VAT",
+						"key": "standard",
+						"rate": "super-reduced",
+						"percent": "5.0%"
+					}
+				],
+				"total": "100.00"
+			}
+		],
+		"totals": {
+			"sum": "1325.00",
+			"total": "1325.00",
+			"taxes": {
+				"categories": [
+					{
+						"code": "VAT",
+						"rates": [
+							{
+								"key": "standard",
+								"base": "1200.00",
+								"percent": "23.0%",
+								"amount": "276.00"
+							},
+							{
+								"key": "standard",
+								"base": "25.00",
+								"percent": "19.0%",
+								"amount": "4.75"
+							},
+							{
+								"key": "standard",
+								"base": "100.00",
+								"percent": "5.0%",
+								"amount": "5.00"
+							}
+						],
+						"amount": "285.75"
+					}
+				],
+				"sum": "285.75"
+			},
+			"tax": "285.75",
+			"total_with_tax": "1610.75",
+			"payable": "1610.75"
+		}
+	}
+}
\ No newline at end of file
diff --git a/regimes/regimes.go b/regimes/regimes.go
index a6b6d7203..dbae5997a 100644
--- a/regimes/regimes.go
+++ b/regimes/regimes.go
@@ -31,5 +31,6 @@ import (
 	_ "github.com/invopop/gobl/regimes/sa"
 	_ "github.com/invopop/gobl/regimes/se"
 	_ "github.com/invopop/gobl/regimes/sg"
+	_ "github.com/invopop/gobl/regimes/sk"
 	_ "github.com/invopop/gobl/regimes/us"
 )
diff --git a/regimes/sk/sk.go b/regimes/sk/sk.go
new file mode 100644
index 000000000..809977e7e
--- /dev/null
+++ b/regimes/sk/sk.go
@@ -0,0 +1,75 @@
+// Package sk provides tax regime support for Slovakia.
+package sk
+
+import (
+	"github.com/invopop/gobl/bill"
+	"github.com/invopop/gobl/cal"
+	"github.com/invopop/gobl/cbc"
+	"github.com/invopop/gobl/currency"
+	"github.com/invopop/gobl/i18n"
+	"github.com/invopop/gobl/norm"
+	"github.com/invopop/gobl/pkg/here"
+	"github.com/invopop/gobl/rules"
+	"github.com/invopop/gobl/tax"
+)
+
+// CountryCode is the ISO 3166-1 alpha-2 code for Slovakia.
+const CountryCode = "SK"
+
+func init() {
+	tax.RegisterRegimeDef(New())
+	rules.Register("sk", rules.GOBL.Add(CountryCode),
+		taxIdentityRules(),
+	)
+	norm.Register(
+		norm.When(tax.IdentityIn(CountryCode), norm.For(func(tID *tax.Identity) { tax.NormalizeIdentity(tID) })),
+	)
+}
+
+// New instantiates a new Slovakia regime.
+func New() *tax.RegimeDef {
+	return &tax.RegimeDef{
+		Country:   CountryCode,
+		Currency:  currency.EUR,
+		TaxScheme: tax.CategoryVAT,
+		Name: i18n.String{
+			i18n.EN: "Slovakia",
+			i18n.SK: "Slovensko",
+		},
+		Description: i18n.String{
+			i18n.EN: here.Doc(`
+				Slovakia's tax system is administered by the Financial Administration of the
+				Slovak Republic (Finančná správa Slovenskej republiky). As an EU member state,
+				Slovakia follows the EU VAT Directive.
+
+				VAT (daň z pridanej hodnoty, DPH) applies at a standard rate, with reduced rates
+				for certain goods and services such as foodstuffs, medicines, medical devices,
+				books, and accommodation. Exports and intra-EU supplies to VAT-registered buyers
+				are zero-rated.
+
+				Businesses registered for VAT are identified by their IČ DPH, formed by the
+				prefix SK followed by ten digits (e.g. SK2020273893).
+			`),
+		},
+		Sources: []*cbc.Source{
+			{
+				Title: i18n.NewString("Finančná správa - Daň z pridanej hodnoty (VAT)"),
+				URL:   "https://www.financnasprava.sk/sk/podnikatelia/dane/dan-z-pridanej-hodnoty",
+				At:    cal.NewDateTime(2026, 8, 6, 0, 0, 0),
+			},
+			{
+				Title: i18n.NewString("Slov-Lex - Zákon č. 222/2004 Z. z. o dani z pridanej hodnoty"),
+				URL:   "https://www.slov-lex.sk/ezbierky/pravne-predpisy/SK/ZZ/2004/222/",
+				At:    cal.NewDateTime(2026, 8, 6, 0, 0, 0),
+			},
+			{
+				Title: i18n.NewString("Financial Administration of the Slovak Republic (English)"),
+				URL:   "https://www.financnasprava.sk/en/",
+				At:    cal.NewDateTime(2026, 8, 6, 0, 0, 0),
+			},
+		},
+		TimeZone:   "Europe/Bratislava",
+		Categories: taxCategories,
+		Scenarios:  []*tax.ScenarioSet{bill.InvoiceScenarios()},
+	}
+}
diff --git a/regimes/sk/tax_categories.go b/regimes/sk/tax_categories.go
new file mode 100644
index 000000000..2a59fc796
--- /dev/null
+++ b/regimes/sk/tax_categories.go
@@ -0,0 +1,101 @@
+package sk
+
+import (
+	"github.com/invopop/gobl/cal"
+	"github.com/invopop/gobl/cbc"
+	"github.com/invopop/gobl/i18n"
+	"github.com/invopop/gobl/num"
+	"github.com/invopop/gobl/tax"
+)
+
+// Slovakia's VAT rates.
+// Only the standard rate carries a pre-2025 value (20%, in force since 2011). The
+// reduced and super-reduced rates are deliberately not backfilled: before 2025 there
+// was a single 10% reduced rate on príloha č. 7 goods (medicines, books), whose scope
+// sits closer to today's 5% super-reduced than to the new 19% tier, so attaching that
+// history to either rate would misrepresent which goods were taxed at which rate.
+var taxCategories = []*tax.CategoryDef{
+	{
+		Code: tax.CategoryVAT,
+		Name: i18n.String{
+			i18n.EN: "VAT",
+			i18n.SK: "DPH",
+		},
+		Title: i18n.String{
+			i18n.EN: "Value Added Tax",
+			i18n.SK: "Daň z pridanej hodnoty",
+		},
+		Sources: []*cbc.Source{
+			{
+				Title: i18n.NewString("Slov-Lex - Zákon č. 222/2004 Z. z. § 27 (Sadzba dane)"),
+				URL:   "https://www.slov-lex.sk/ezbierky/pravne-predpisy/SK/ZZ/2004/222/",
+				At:    cal.NewDateTime(2026, 8, 6, 0, 0, 0),
+			},
+			{
+				// Source of the 20% standard rate, introduced from 2011-01-01 by § 85j and
+				// carried in § 27 itself from 2015-01-01.
+				Title: i18n.NewString("Slov-Lex - Zákon č. 490/2010 Z. z. (novela zákona č. 222/2004 Z. z.)"),
+				URL:   "https://www.slov-lex.sk/ezbierky/pravne-predpisy/SK/ZZ/2010/490/",
+				At:    cal.NewDateTime(2026, 8, 6, 0, 0, 0),
+			},
+		},
+		Retained: false,
+		Keys:     tax.GlobalVATKeys(),
+		Rates: []*tax.RateDef{
+			{
+				Keys: []cbc.Key{tax.KeyStandard},
+				Rate: tax.RateGeneral,
+				Name: i18n.String{
+					i18n.EN: "Standard Rate",
+					i18n.SK: "Základná sadzba",
+				},
+				Values: []*tax.RateValueDef{
+					{
+						Since:   cal.NewDate(2025, 1, 1),
+						Percent: num.MakePercentage(230, 3), // 23.0%
+					},
+					{
+						Since:   cal.NewDate(2011, 1, 1),
+						Percent: num.MakePercentage(200, 3), // 20.0%
+					},
+				},
+			},
+			{
+				Keys: []cbc.Key{tax.KeyStandard},
+				Rate: tax.RateReduced,
+				Name: i18n.String{
+					i18n.EN: "Reduced Rate",
+					i18n.SK: "Znížená sadzba",
+				},
+				Description: i18n.String{
+					i18n.EN: "Non-basic foodstuffs, electricity and certain catering services.",
+					i18n.SK: "Potraviny okrem základných, elektrina a niektoré reštauračné služby.",
+				},
+				Values: []*tax.RateValueDef{
+					{
+						Since:   cal.NewDate(2025, 1, 1),
+						Percent: num.MakePercentage(190, 3), // 19.0%
+					},
+				},
+			},
+			{
+				Keys: []cbc.Key{tax.KeyStandard},
+				Rate: tax.RateSuperReduced,
+				Name: i18n.String{
+					i18n.EN: "Super-reduced Rate",
+					i18n.SK: "Druhá znížená sadzba",
+				},
+				Description: i18n.String{
+					i18n.EN: "Basic foodstuffs, medicines, medical devices, books, and accommodation.",
+					i18n.SK: "Základné potraviny, lieky, zdravotnícke pomôcky, knihy a ubytovanie.",
+				},
+				Values: []*tax.RateValueDef{
+					{
+						Since:   cal.NewDate(2025, 1, 1),
+						Percent: num.MakePercentage(50, 3), // 5.0%
+					},
+				},
+			},
+		},
+	},
+}
diff --git a/regimes/sk/tax_identity.go b/regimes/sk/tax_identity.go
new file mode 100644
index 000000000..c3567f075
--- /dev/null
+++ b/regimes/sk/tax_identity.go
@@ -0,0 +1,50 @@
+package sk
+
+import (
+	"regexp"
+	"strconv"
+
+	"github.com/invopop/gobl/rules"
+	"github.com/invopop/gobl/rules/is"
+	"github.com/invopop/gobl/tax"
+)
+
+// taxCodeRegexp matches a normalized Slovak IČ DPH: exactly 10 digits, the first
+// of which is non-zero. The "SK" country prefix, spaces and hyphens are removed
+// during normalization (tax.NormalizeIdentity), so only the digits reach this
+// validation.
+var taxCodeRegexp = regexp.MustCompile(`^[1-9]\d{9}$`)
+
+func taxIdentityRules() *rules.Set {
+	return rules.For(new(tax.Identity),
+		rules.When(tax.IdentityIn(CountryCode),
+			rules.Field("code",
+				rules.AssertIfPresent("01", "tax identity code for SK must be 10 digits starting with 1-9",
+					is.MatchesRegexp(taxCodeRegexp),
+				),
+				rules.AssertIfPresent("02", "tax identity code for SK failed the checksum: the 10 digit number must be divisible by 11",
+					is.StringFunc("checksum", validateTaxCodeChecksum),
+				),
+			),
+		),
+	)
+}
+
+// validateTaxCodeChecksum applies the Slovak IČ DPH checksum: the whole 10-digit
+// number must be divisible by 11. Each assertion is evaluated independently, so a
+// code that already failed the format rule still reaches this function; ParseInt
+// rejects anything that is not a plain integer.
+//
+// Note: the Slovak tax authority does not publish this algorithm; the modulo-11
+// rule is consistently documented by EU VAT-number validators and matches all
+// known valid identifiers (e.g. SK2020273893).
+//
+// Reference: https://github.com/ltns35/go-vat/blob/main/countries/slovakia.go
+// Reference: https://vatdb.com/guides/validate-sk-vat-number/
+func validateTaxCodeChecksum(code string) bool {
+	n, err := strconv.ParseInt(code, 10, 64)
+	if err != nil {
+		return false
+	}
+	return n%11 == 0
+}
diff --git a/regimes/sk/tax_identity_test.go b/regimes/sk/tax_identity_test.go
new file mode 100644
index 000000000..d257034fa
--- /dev/null
+++ b/regimes/sk/tax_identity_test.go
@@ -0,0 +1,141 @@
+package sk_test
+
+import (
+	"slices"
+	"testing"
+
+	"github.com/invopop/gobl/cbc"
+	"github.com/invopop/gobl/norm"
+	"github.com/invopop/gobl/rules"
+	"github.com/invopop/gobl/tax"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestTaxIdentityRules(t *testing.T) {
+	// The format and checksum rules are asserted separately, so a code may
+	// trigger either or both. Codes not listed must NOT be reported.
+	allCodes := []string{"IDENTITY-01", "IDENTITY-02"}
+
+	tests := []struct {
+		name         string
+		inputCode    cbc.Code
+		expectedErrs []string
+	}{
+		{
+			name:      "valid divisible by 11",
+			inputCode: "2020273893",
+		},
+		{
+			name:      "valid divisible by 11, natural person",
+			inputCode: "7120001713",
+		},
+		{
+			name:      "empty code",
+			inputCode: "",
+		},
+		{
+			name:         "leading zero, checksum still valid",
+			inputCode:    "0000000011",
+			expectedErrs: []string{"IDENTITY-01"},
+		},
+		{
+			name:         "all zeros, checksum still valid",
+			inputCode:    "0000000000",
+			expectedErrs: []string{"IDENTITY-01"},
+		},
+		{
+			name:         "well formed but not divisible by 11",
+			inputCode:    "2020273894",
+			expectedErrs: []string{"IDENTITY-02"},
+		},
+		{
+			name:         "too short",
+			inputCode:    "202027389",
+			expectedErrs: []string{"IDENTITY-01", "IDENTITY-02"},
+		},
+		{
+			name:         "too long",
+			inputCode:    "20202738931",
+			expectedErrs: []string{"IDENTITY-01", "IDENTITY-02"},
+		},
+		{
+			name:         "contains letters",
+			inputCode:    "202027389A",
+			expectedErrs: []string{"IDENTITY-01", "IDENTITY-02"},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			tID := &tax.Identity{Country: "SK", Code: tt.inputCode}
+			err := rules.Validate(tID)
+			if len(tt.expectedErrs) == 0 {
+				assert.NoError(t, err)
+				return
+			}
+			if !assert.Error(t, err) {
+				return
+			}
+			for _, code := range allCodes {
+				if slices.Contains(tt.expectedErrs, code) {
+					assert.Contains(t, err.Error(), code)
+				} else {
+					assert.NotContains(t, err.Error(), code)
+				}
+			}
+		})
+	}
+}
+
+func TestNormalizeTaxIdentity(t *testing.T) {
+	tests := []struct {
+		name         string
+		inputCode    cbc.Code
+		expectedCode cbc.Code
+	}{
+		{
+			name:         "strips SK prefix",
+			inputCode:    "SK2020273893",
+			expectedCode: "2020273893",
+		},
+		{
+			name:         "strips lowercase prefix",
+			inputCode:    "sk2020273893",
+			expectedCode: "2020273893",
+		},
+		{
+			name:         "strips spaces",
+			inputCode:    "2020 2738 93",
+			expectedCode: "2020273893",
+		},
+		{
+			name:         "strips hyphen",
+			inputCode:    "20202-73893",
+			expectedCode: "2020273893",
+		},
+		{
+			name:         "already normalized",
+			inputCode:    "2020273893",
+			expectedCode: "2020273893",
+		},
+		{
+			name:         "empty",
+			inputCode:    "",
+			expectedCode: "",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			tID := &tax.Identity{Country: "SK", Code: tt.inputCode}
+			norm.Normalize(tID)
+			assert.Equal(t, tt.expectedCode, tID.Code)
+		})
+	}
+
+	t.Run("nil identity", func(t *testing.T) {
+		assert.NotPanics(t, func() {
+			norm.Normalize((*tax.Identity)(nil))
+		})
+	})
+}