diff --git a/bill/invoice.go b/bill/invoice.go
index 42a550f4..9f2595f8 100644
--- a/bill/invoice.go
+++ b/bill/invoice.go
@@ -145,6 +145,8 @@ func (inv *Invoice) ValidateWithContext(ctx context.Context) error {
 
 		validation.Field(&inv.Notes),
 		validation.Field(&inv.Meta),
+
+		validation.Field(&inv.Complements, validation.Each()),
 	)
 	if err == nil {
 		err = r.ValidateObject(inv)
@@ -466,6 +468,20 @@ func (inv *Invoice) calculate(r *tax.Regime, tID *tax.Identity) error {
 
 	t.round(zero)
 
+	// Complements
+	if err := calculateComplements(inv.Complements); err != nil {
+		return validation.Errors{"complements": err}
+	}
+
+	return nil
+}
+
+func calculateComplements(comps []*schema.Object) error {
+	for _, c := range comps {
+		if err := c.Calculate(); err != nil {
+			return err
+		}
+	}
 	return nil
 }
 
diff --git a/regimes/mx/examples/fuel-account-balance.yaml b/regimes/mx/examples/fuel-account-balance.yaml
new file mode 100644
index 00000000..e8d2b318
--- /dev/null
+++ b/regimes/mx/examples/fuel-account-balance.yaml
@@ -0,0 +1,78 @@
+$schema: "https://gobl.org/draft-0/bill/invoice"
+issue_date: "2023-07-10"
+series: "TEST"
+code: "00002"
+supplier:
+  name: "ESCUELA KEMPER URGATE"
+  ext:
+    mx-cfdi-fiscal-regime: "601"
+  tax_id:
+    country: "MX"
+    code: "EKU9003173C9"
+    zone: "21000"
+customer:
+  name: "UNIVERSIDAD ROBOTICA ESPAÑOLA"
+  ext:
+    mx-cfdi-fiscal-regime: "601"
+    mx-cfdi-use: "G01"
+  tax_id:
+    country: "MX"
+    code: "URE180429TM6"
+    zone: "86991"
+lines:
+  - quantity: "1"
+    item:
+      name: "Comisión servicio de monedero electrónico"
+      price: "10.00"
+      ext:
+        mx-cfdi-prod-serv: "84141602"
+    taxes:
+      - cat: "VAT"
+        rate: "standard"
+payment:
+  terms:
+    notes: "Condiciones de pago"
+  instructions:
+    key: "online+wallet"
+complements:
+  - $schema: "https://gobl.org/draft-0/regimes/mx/fuel-account-balance"
+    account_number: "0123456789"
+    lines:
+      - e_wallet_id: "1234"
+        purchase_date_time: "2022-07-19T10:20:30"
+        vendor_tax_code: "RWT860605OF5"
+        service_station_code: "8171650"
+        quantity: "9.6613"
+        item:
+          unit: "l"
+          type: "3"
+          name: "Diesel"
+          price: "12.7428"
+        purchase_code: "2794668"
+        total: "123.11"
+        taxes:
+          - code: "IVA"
+            rate: "0.16"
+            amount: "19.70"
+          - code: "IEPS"
+            rate: "5.9195"
+            amount: "57.19"
+      - e_wallet_id: "1234"
+        purchase_date_time: "2022-08-19T10:20:30"
+        vendor_tax_code: "DJV320816JT1"
+        service_station_code: "8171667"
+        quantity: "9.68"
+        item:
+          type: "1"
+          name: "Gasolina Magna"
+          price: "12.709"
+        purchase_code: "2794669"
+        total: "123.02"
+        taxes:
+          - code: "IVA"
+            rate: "0.16"
+            amount: "19.68"
+          - code: "IEPS"
+            rate: "5.9195"
+            amount: "57.30"
+
diff --git a/regimes/mx/examples/out/fuel-account-balance.json b/regimes/mx/examples/out/fuel-account-balance.json
new file mode 100644
index 00000000..a5094a88
--- /dev/null
+++ b/regimes/mx/examples/out/fuel-account-balance.json
@@ -0,0 +1,159 @@
+{
+	"$schema": "https://gobl.org/draft-0/envelope",
+	"head": {
+		"uuid": "8a51fd30-2a27-11ee-be56-0242ac120002",
+		"dig": {
+			"alg": "sha256",
+			"val": "1451d94f4ab432342eb1cf5721e978ff88bf45a90835c0538a917b58b9d59224"
+		},
+		"draft": true
+	},
+	"doc": {
+		"$schema": "https://gobl.org/draft-0/bill/invoice",
+		"type": "standard",
+		"series": "TEST",
+		"code": "00002",
+		"issue_date": "2023-07-10",
+		"currency": "MXN",
+		"supplier": {
+			"name": "ESCUELA KEMPER URGATE",
+			"tax_id": {
+				"country": "MX",
+				"zone": "21000",
+				"code": "EKU9003173C9"
+			},
+			"ext": {
+				"mx-cfdi-fiscal-regime": "601"
+			}
+		},
+		"customer": {
+			"name": "UNIVERSIDAD ROBOTICA ESPAÑOLA",
+			"tax_id": {
+				"country": "MX",
+				"zone": "86991",
+				"code": "URE180429TM6"
+			},
+			"ext": {
+				"mx-cfdi-fiscal-regime": "601",
+				"mx-cfdi-use": "G01"
+			}
+		},
+		"lines": [
+			{
+				"i": 1,
+				"quantity": "1",
+				"item": {
+					"name": "Comisión servicio de monedero electrónico",
+					"price": "10.00",
+					"ext": {
+						"mx-cfdi-prod-serv": "84141602"
+					}
+				},
+				"sum": "10.00",
+				"taxes": [
+					{
+						"cat": "VAT",
+						"rate": "standard",
+						"percent": "16.0%"
+					}
+				],
+				"total": "10.00"
+			}
+		],
+		"payment": {
+			"terms": {
+				"notes": "Condiciones de pago"
+			},
+			"instructions": {
+				"key": "online+wallet"
+			}
+		},
+		"totals": {
+			"sum": "10.00",
+			"total": "10.00",
+			"taxes": {
+				"categories": [
+					{
+						"code": "VAT",
+						"rates": [
+							{
+								"key": "standard",
+								"base": "10.00",
+								"percent": "16.0%",
+								"amount": "1.60"
+							}
+						],
+						"amount": "1.60"
+					}
+				],
+				"sum": "1.60"
+			},
+			"tax": "1.60",
+			"total_with_tax": "11.60",
+			"payable": "11.60"
+		},
+		"complements": [
+			{
+				"$schema": "https://gobl.org/draft-0/regimes/mx/fuel-account-balance",
+				"account_number": "0123456789",
+				"subtotal": "246.13",
+				"total": "400.00",
+				"lines": [
+					{
+						"e_wallet_id": "1234",
+						"purchase_date_time": "2022-07-19T10:20:30",
+						"vendor_tax_code": "RWT860605OF5",
+						"service_station_code": "8171650",
+						"quantity": "9.661",
+						"item": {
+							"type": "3",
+							"unit": "l",
+							"name": "Diesel",
+							"price": "12.743"
+						},
+						"purchase_code": "2794668",
+						"total": "123.11",
+						"taxes": [
+							{
+								"code": "IVA",
+								"rate": "0.160000",
+								"amount": "19.70"
+							},
+							{
+								"code": "IEPS",
+								"rate": "5.919500",
+								"amount": "57.19"
+							}
+						]
+					},
+					{
+						"e_wallet_id": "1234",
+						"purchase_date_time": "2022-08-19T10:20:30",
+						"vendor_tax_code": "DJV320816JT1",
+						"service_station_code": "8171667",
+						"quantity": "9.680",
+						"item": {
+							"type": "1",
+							"name": "Gasolina Magna",
+							"price": "12.709"
+						},
+						"purchase_code": "2794669",
+						"total": "123.02",
+						"taxes": [
+							{
+								"code": "IVA",
+								"rate": "0.160000",
+								"amount": "19.68"
+							},
+							{
+								"code": "IEPS",
+								"rate": "5.919500",
+								"amount": "57.30"
+							}
+						]
+					}
+				]
+			}
+		]
+	}
+}
\ No newline at end of file
diff --git a/regimes/mx/fuel_account_balance.go b/regimes/mx/fuel_account_balance.go
new file mode 100644
index 00000000..5b9a7179
--- /dev/null
+++ b/regimes/mx/fuel_account_balance.go
@@ -0,0 +1,197 @@
+package mx
+
+import (
+	"github.com/invopop/gobl/cal"
+	"github.com/invopop/gobl/cbc"
+	"github.com/invopop/gobl/num"
+	"github.com/invopop/gobl/org"
+	"github.com/invopop/validation"
+)
+
+// Constants for the precision of complement's amounts
+const (
+	FuelAccountInterimPrecision = 3
+	FuelAccountFinalPrecision   = 2
+	FuelAccountRatePrecision    = 6
+)
+
+// Constants for the complement's allowed tax codes
+const (
+	FuelAccountTaxCodeVAT  = cbc.Code("IVA")
+	FuelAccountTaxCodeIEPS = cbc.Code("IEPS")
+)
+
+// FuelAccountValidTaxCodes lists of the complement's allowed tax codes
+var FuelAccountValidTaxCodes = []interface{}{
+	FuelAccountTaxCodeVAT,
+	FuelAccountTaxCodeIEPS,
+}
+
+// FuelAccountBalance carries the data to produce a CFDI's "Complemento de
+// Estado de Cuenta de Combustibles para Monederos Electrónicos" (version 1.2
+// revision B) providing detailed information about fuel purchases made with
+// electronic wallets. In Mexico, e-wallet suppliers are required to report this
+// complementary information in the invoices they issue to their customers.
+//
+// This struct maps to the `EstadoDeCuentaCombustible` root node in the CFDI's
+// complement.
+type FuelAccountBalance struct {
+	// Customer's account number (maps to `NumeroDeCuenta`).
+	AccountNumber string `json:"account_number" jsonschema:"title=Account Number"`
+	// Sum of all line totals (i.e. taxes not included) (calculated, maps to `SubTotal`).
+	Subtotal num.Amount `json:"subtotal" jsonschema:"title=Subtotal" jsonschema_extras:"calculated=true"`
+	// Grand total after taxes have been applied (calculated, maps to `Total`).
+	Total num.Amount `json:"total" jsonschema:"title=Total" jsonschema_extras:"calculated=true"`
+	// List of fuel purchases made with the customer's e-wallets (maps to `Conceptos`).
+	Lines []*FuelAccountLine `json:"lines" jsonschema:"title=Lines"`
+}
+
+// FuelAccountLine represents a single fuel purchase made with an e-wallet
+// issued by the invoice's supplier. It maps to one
+// `ConceptoEstadoDeCuentaCombustible` node in the CFDI's complement.
+type FuelAccountLine struct {
+	// Identifier of the e-wallet used to make the purchase (maps to `Identificador`).
+	EWalletID cbc.Code `json:"e_wallet_id" jsonschema:"title=E-wallet Identifier"`
+	// Date and time of the purchase (maps to `Fecha`).
+	PurchaseDateTime cal.DateTime `json:"purchase_date_time" jsonschema:"title=Purchase Date and Time"`
+	// Tax Identity Code of the fuel's vendor (maps to `Rfc`)
+	VendorTaxCode cbc.Code `json:"vendor_tax_code" jsonschema:"title=Vendor's Tax Identity Code"`
+	// Code of the service station where the purchase was made (maps to `ClaveEstacion`).
+	ServiceStationCode cbc.Code `json:"service_station_code" jsonschema:"title=Service Station Code"`
+	// Amount of fuel units purchased (maps to `Cantidad`)
+	Quantity num.Amount `json:"quantity" jsonschema:"title=Quantity"`
+	// Details of the fuel purchased.
+	Item *FuelAccountItem `json:"item" jsonschema:"title=Item"`
+	// Identifier of the purchase (maps to `FolioOperacion`).
+	PurchaseCode cbc.Code `json:"purchase_code" jsonschema:"title=Purchase Code"`
+	// Result of quantity multiplied by the unit price (maps to `Importe`).
+	Total num.Amount `json:"total" jsonschema:"title=Total"`
+	// Map of taxes applied to the purchase (maps to `Traslados`).
+	Taxes []*FuelAccountTax `json:"taxes" jsonschema:"title=Taxes"`
+}
+
+// FuelAccountItem provides the details of a fuel purchase. Its fields map to
+// attributes of the `ConceptoEstadoDeCuentaCombustible` node in the CFDI's
+// complement.
+type FuelAccountItem struct {
+	// Type of fuel (one of `c_ClaveTipoCombustible` codes, maps to `TipoCombustible`).
+	Type cbc.Code `json:"type" jsonschema:"title=Type"`
+	// Reference unit of measure used in the price and the quantity (maps to `Unidad`).
+	Unit org.Unit `json:"unit,omitempty" jsonschema:"title=Unit"`
+	// Name of the fuel (maps to `NombreCombustible`).
+	Name string `json:"name" jsonschema:"title=Name"`
+	// Base price of a single unit of the fuel without taxes (maps to `ValorUnitario`).
+	Price num.Amount `json:"price" jsonschema:"title=Price"`
+}
+
+// FuelAccountTax represents a single tax applied to a fuel purchase. It maps to
+// one `Traslado` node in the CFDI's complement.
+type FuelAccountTax struct {
+	// Code that identifies the tax ("IVA" or "IEPS", maps to `Impuesto`)
+	Code cbc.Code `json:"code" jsonschema:"title=Code"`
+	// Rate applicable to either the line total (tasa) or the line quantity (cuota) (maps to `TasaOCuota`).
+	Rate num.Amount `json:"rate" jsonschema:"title=Rate"`
+	// Total amount of the tax once the rate has been applied (maps to `Importe`).
+	Amount num.Amount `json:"amount" jsonschema:"title=Amount"`
+}
+
+// Validate ensures that the complement's data is valid.
+func (fab *FuelAccountBalance) Validate() error {
+	return validation.ValidateStruct(fab,
+		validation.Field(&fab.AccountNumber,
+			validation.Required,
+			validation.Length(1, 50),
+		),
+		validation.Field(&fab.Subtotal, validation.Required),
+		validation.Field(&fab.Total, validation.Required),
+		validation.Field(&fab.Lines, validation.Required),
+	)
+}
+
+// Validate ensures that the line's data is valid.
+func (fal *FuelAccountLine) Validate() error {
+	return validation.ValidateStruct(fal,
+		validation.Field(&fal.EWalletID, validation.Required),
+		validation.Field(&fal.PurchaseDateTime, cal.DateTimeNotZero()),
+		validation.Field(&fal.VendorTaxCode,
+			validation.Required,
+			validation.By(validateTaxCode),
+		),
+		validation.Field(&fal.ServiceStationCode,
+			validation.Required,
+			validation.Length(1, 20),
+		),
+		validation.Field(&fal.Quantity, num.Positive),
+		validation.Field(&fal.Item, validation.Required),
+
+		validation.Field(&fal.PurchaseCode,
+			validation.Required,
+			validation.Length(1, 50),
+		),
+		validation.Field(&fal.Total, isValidLineTotal(fal)),
+		validation.Field(&fal.Taxes, validation.Required),
+	)
+}
+
+// Validate ensures that the item's data is valid.
+func (fai *FuelAccountItem) Validate() error {
+	return validation.ValidateStruct(fai,
+		validation.Field(&fai.Type, validation.Required),
+		validation.Field(&fai.Name,
+			validation.Required,
+			validation.Length(1, 300),
+		),
+		validation.Field(&fai.Price, num.Positive),
+	)
+}
+
+// Validate ensures that the tax's data is valid.
+func (fat *FuelAccountTax) Validate() error {
+	return validation.ValidateStruct(fat,
+		validation.Field(&fat.Code,
+			validation.Required,
+			validation.In(FuelAccountValidTaxCodes...),
+		),
+		validation.Field(&fat.Rate, num.Positive),
+		validation.Field(&fat.Amount, num.Positive),
+	)
+}
+
+func isValidLineTotal(line *FuelAccountLine) validation.Rule {
+	if line.Item == nil {
+		return validation.Skip
+	}
+
+	expected := line.Quantity.Multiply(line.Item.Price).Rescale(2)
+
+	return validation.In(expected).Error("must be quantity x unit_price")
+}
+
+// Calculate performs the complement's calculations and normalisations.
+func (fab *FuelAccountBalance) Calculate() error {
+	var subtotal, taxtotal num.Amount
+
+	for _, l := range fab.Lines {
+		// Normalise amounts to the expected precision
+		if l.Item != nil {
+			l.Item.Price = l.Item.Price.Rescale(FuelAccountInterimPrecision)
+		}
+		l.Quantity = l.Quantity.Rescale(FuelAccountInterimPrecision)
+		l.Total = l.Total.Rescale(FuelAccountFinalPrecision)
+
+		subtotal = l.Total.Add(subtotal)
+
+		for _, t := range l.Taxes {
+			// Normalise amounts to the expected precision
+			t.Rate = t.Rate.Rescale(FuelAccountRatePrecision)
+			t.Amount = t.Amount.Rescale(FuelAccountFinalPrecision)
+
+			taxtotal = t.Amount.Add(taxtotal)
+		}
+	}
+
+	fab.Subtotal = subtotal.Rescale(FuelAccountFinalPrecision)
+	fab.Total = subtotal.Add(taxtotal).Rescale(FuelAccountFinalPrecision)
+
+	return nil
+}
diff --git a/regimes/mx/fuel_account_balance_test.go b/regimes/mx/fuel_account_balance_test.go
new file mode 100644
index 00000000..e7ab1e49
--- /dev/null
+++ b/regimes/mx/fuel_account_balance_test.go
@@ -0,0 +1,118 @@
+package mx_test
+
+import (
+	"testing"
+
+	"github.com/invopop/gobl/num"
+	"github.com/invopop/gobl/regimes/mx"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestInvalidComplement(t *testing.T) {
+	fab := &mx.FuelAccountBalance{}
+
+	err := fab.Validate()
+
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "account_number: cannot be blank")
+	assert.Contains(t, err.Error(), "lines: cannot be blank")
+}
+
+func TestInvalidLine(t *testing.T) {
+	fab := &mx.FuelAccountBalance{Lines: []*mx.FuelAccountLine{{}}}
+
+	err := fab.Validate()
+
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "e_wallet_id: cannot be blank")
+	assert.Contains(t, err.Error(), "purchase_date_time: required")
+	assert.Contains(t, err.Error(), "vendor_tax_code: cannot be blank")
+	assert.Contains(t, err.Error(), "service_station_code: cannot be blank")
+	assert.Contains(t, err.Error(), "quantity: must be greater than 0")
+	assert.Contains(t, err.Error(), "item: cannot be blank")
+	assert.Contains(t, err.Error(), "purchase_code: cannot be blank")
+	assert.Contains(t, err.Error(), "taxes: cannot be blank")
+
+	fab.Lines[0].VendorTaxCode = "1234"
+	fab.Lines[0].Quantity = num.MakeAmount(1, 0)
+	fab.Lines[0].Item = &mx.FuelAccountItem{Price: num.MakeAmount(1, 0)}
+
+	err = fab.Validate()
+
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "vendor_tax_code: invalid tax identity code")
+	assert.Contains(t, err.Error(), "total: must be quantity x unit_price")
+}
+
+func TestInvalidItem(t *testing.T) {
+	fab := &mx.FuelAccountBalance{Lines: []*mx.FuelAccountLine{
+		{Item: &mx.FuelAccountItem{}}},
+	}
+
+	err := fab.Validate()
+
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "type: cannot be blank")
+	assert.Contains(t, err.Error(), "name: cannot be blank")
+	assert.Contains(t, err.Error(), "price: must be greater than 0")
+}
+
+func TestInvalidTax(t *testing.T) {
+	fab := &mx.FuelAccountBalance{Lines: []*mx.FuelAccountLine{
+		{Taxes: []*mx.FuelAccountTax{{}}}},
+	}
+
+	err := fab.Validate()
+
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "code: cannot be blank")
+	assert.Contains(t, err.Error(), "rate: must be greater than 0")
+	assert.Contains(t, err.Error(), "amount: must be greater than 0")
+
+	fab.Lines[0].Taxes[0].Code = "IRPF"
+
+	err = fab.Validate()
+
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "code: must be a valid value")
+}
+
+func TestCalculate(t *testing.T) {
+	fab := &mx.FuelAccountBalance{
+		Lines: []*mx.FuelAccountLine{
+			{
+				Quantity: num.MakeAmount(11, 1),
+				Item:     &mx.FuelAccountItem{Price: num.MakeAmount(9091, 2)},
+				Total:    num.MakeAmount(100, 0),
+				Taxes: []*mx.FuelAccountTax{
+					{
+						Rate:   num.MakeAmount(16, 2),
+						Amount: num.MakeAmount(16, 0),
+					},
+					{Amount: num.MakeAmount(56789, 4)},
+				},
+			},
+			{
+				Total: num.MakeAmount(100009, 3),
+				Taxes: []*mx.FuelAccountTax{
+					{Amount: num.MakeAmount(16, 0)},
+					{Amount: num.MakeAmount(56789, 4)},
+				},
+			},
+		},
+	}
+
+	err := fab.Calculate()
+
+	require.NoError(t, err)
+	assert.Equal(t, num.MakeAmount(20001, 2), fab.Subtotal)
+	assert.Equal(t, num.MakeAmount(24337, 2), fab.Total)
+
+	assert.Equal(t, num.MakeAmount(1100, 3), fab.Lines[0].Quantity)
+	assert.Equal(t, num.MakeAmount(90910, 3), fab.Lines[0].Item.Price)
+	assert.Equal(t, num.MakeAmount(10000, 2), fab.Lines[0].Total)
+
+	assert.Equal(t, num.MakeAmount(160000, 6), fab.Lines[0].Taxes[0].Rate)
+	assert.Equal(t, num.MakeAmount(1600, 2), fab.Lines[0].Taxes[0].Amount)
+}
diff --git a/regimes/mx/mx.go b/regimes/mx/mx.go
index e65f0ed3..09a88c0a 100644
--- a/regimes/mx/mx.go
+++ b/regimes/mx/mx.go
@@ -9,11 +9,15 @@ import (
 	"github.com/invopop/gobl/l10n"
 	"github.com/invopop/gobl/org"
 	"github.com/invopop/gobl/regimes/common"
+	"github.com/invopop/gobl/schema"
 	"github.com/invopop/gobl/tax"
 )
 
 func init() {
 	tax.RegisterRegime(New())
+
+	// MX GOBL Schema Complements
+	schema.Register(schema.GOBL.Add("regimes/mx"), FuelAccountBalance{})
 }
 
 // Custom keys used typically in meta or codes information.