diff --git a/catalog/address_test.go b/catalog/address_test.go
new file mode 100644
index 0000000..ca4a57a
--- /dev/null
+++ b/catalog/address_test.go
@@ -0,0 +1,28 @@
+package catalog
+
+import "testing"
+
+func TestMergeAddressesDedup(t *testing.T) {
+	dst := []Address{{Street: "Weg 1", City: "Stadt", Zip: "1"}}
+	got := mergeAddresses(dst, []Address{
+		{Street: "weg 1", City: "stadt", Zip: "1"}, // duplicate (case-insensitive)
+		{Street: "Weg 2", City: "Stadt", Zip: "2"}, // new
+	})
+	if len(got) != 2 {
+		t.Fatalf("got %d addresses, want 2: %+v", len(got), got)
+	}
+	if got[1].Street != "Weg 2" {
+		t.Errorf("second = %+v", got[1])
+	}
+}
+
+func TestEntryAddressesYAML(t *testing.T) {
+	doc := &Document{Entries: []Entry{{
+		ID: "person:max maier", Kind: "person", Name: "Max Maier",
+		Addresses: []Address{{Street: "Weg 1", City: "Stadt", Zip: "12345", Category: "Billing", Primary: true}},
+	}}}
+	merged := MergeDocs(doc)
+	if len(merged.Entries) != 1 || len(merged.Entries[0].Addresses) != 1 {
+		t.Fatalf("merged = %+v", merged.Entries)
+	}
+}
diff --git a/catalog/apply.go b/catalog/apply.go
index bed3990..2f5094e 100644
--- a/catalog/apply.go
+++ b/catalog/apply.go
@@ -195,5 +195,16 @@ func ensureContactInfos(ctx context.Context, client *onlyoffice.Client, contactI
 			return fmt.Errorf("add phone %s: %w", ph, err)
 		}
 	}
+	for _, a := range e.Addresses {
+		if strings.TrimSpace(a.Street) == "" && strings.TrimSpace(a.City) == "" && strings.TrimSpace(a.Zip) == "" {
+			continue
+		}
+		if onlyoffice.HasContactAddress(existing, a.Street, a.City, a.Zip, a.Category) {
+			continue
+		}
+		if _, err := client.AddContactAddress(ctx, contactID, a.Street, a.City, a.State, a.Zip, a.Country, a.Category, a.Primary); err != nil {
+			return fmt.Errorf("add address %s: %w", strings.TrimSpace(a.Street), err)
+		}
+	}
 	return nil
 }
diff --git a/catalog/types.go b/catalog/types.go
index 0a5a243..5bc0e95 100644
--- a/catalog/types.go
+++ b/catalog/types.go
@@ -12,25 +12,38 @@ import (
 	"gopkg.in/yaml.v3"
 )
 
+// Address is one postal address of a catalog row. Category is the OO
+// AddressCategory label (Home|Postal|Office|Billing|Other|Work).
+type Address struct {
+	Street   string `yaml:"street,omitempty"`
+	City     string `yaml:"city,omitempty"`
+	State    string `yaml:"state,omitempty"`
+	Zip      string `yaml:"zip,omitempty"`
+	Country  string `yaml:"country,omitempty"`
+	Category string `yaml:"category,omitempty"`
+	Primary  bool   `yaml:"primary,omitempty"`
+}
+
 // Entry is one catalog row (person or company).
 type Entry struct {
-	ID      string   `yaml:"id"`
-	Kind    string   `yaml:"kind"` // person | company
-	Name    string   `yaml:"name,omitempty"`
-	First   string   `yaml:"first,omitempty"`
-	Last    string   `yaml:"last,omitempty"`
-	Emails  []string `yaml:"emails,omitempty"`
-	Phones  []string `yaml:"phones,omitempty"`
-	Org     string   `yaml:"org,omitempty"`
-	Sources []string `yaml:"sources,omitempty"`
-	Zone    string   `yaml:"zone"`
-	Role    string   `yaml:"role"`
-	OOID    string   `yaml:"oo_id,omitempty"`
-	Approve bool     `yaml:"approve"`
-	Status  string   `yaml:"status,omitempty"` // new | exists | conflict | applied | skipped
-	Notes   string   `yaml:"notes,omitempty"`
-	Remote  string   `yaml:"remote,omitempty"`
-	GitRoot string   `yaml:"git_root,omitempty"`
+	ID        string    `yaml:"id"`
+	Kind      string    `yaml:"kind"` // person | company
+	Name      string    `yaml:"name,omitempty"`
+	First     string    `yaml:"first,omitempty"`
+	Last      string    `yaml:"last,omitempty"`
+	Emails    []string  `yaml:"emails,omitempty"`
+	Phones    []string  `yaml:"phones,omitempty"`
+	Addresses []Address `yaml:"addresses,omitempty"`
+	Org       string    `yaml:"org,omitempty"`
+	Sources   []string  `yaml:"sources,omitempty"`
+	Zone      string    `yaml:"zone"`
+	Role      string    `yaml:"role"`
+	OOID      string    `yaml:"oo_id,omitempty"`
+	Approve   bool      `yaml:"approve"`
+	Status    string    `yaml:"status,omitempty"` // new | exists | conflict | applied | skipped
+	Notes     string    `yaml:"notes,omitempty"`
+	Remote    string    `yaml:"remote,omitempty"`
+	GitRoot   string    `yaml:"git_root,omitempty"`
 }
 
 // Document is the on-disk catalog file.
@@ -136,6 +149,7 @@ func mergeEntry(dst, src *Entry) {
 	dst.Sources = uniqueStrings(append(dst.Sources, src.Sources...))
 	dst.Emails = uniqueEmails(append(dst.Emails, src.Emails...))
 	dst.Phones = uniqueStrings(append(dst.Phones, src.Phones...))
+	dst.Addresses = mergeAddresses(dst.Addresses, src.Addresses)
 	if dst.First == "" {
 		dst.First = src.First
 	}
@@ -176,6 +190,25 @@ func mergeEntry(dst, src *Entry) {
 	}
 }
 
+// mergeAddresses appends src addresses not already present (by street/city/zip).
+func mergeAddresses(dst, src []Address) []Address {
+	for _, a := range src {
+		exists := false
+		for _, b := range dst {
+			if strings.EqualFold(strings.TrimSpace(a.Street), strings.TrimSpace(b.Street)) &&
+				strings.EqualFold(strings.TrimSpace(a.City), strings.TrimSpace(b.City)) &&
+				strings.EqualFold(strings.TrimSpace(a.Zip), strings.TrimSpace(b.Zip)) {
+				exists = true
+				break
+			}
+		}
+		if !exists {
+			dst = append(dst, a)
+		}
+	}
+	return dst
+}
+
 func uniqueEmails(in []string) []string {
 	seen := map[string]struct{}{}
 	var out []string
diff --git a/crm_address.go b/crm_address.go
new file mode 100644
index 0000000..4bdc3aa
--- /dev/null
+++ b/crm_address.go
@@ -0,0 +1,91 @@
+package onlyoffice
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+// addressCategoryCodes maps ASC.CRM.Core.AddressCategory names to their numeric
+// codes. The OO API expects the code, the UI/docs use the label.
+var addressCategoryCodes = map[string]int{
+	"home":    0,
+	"postal":  1,
+	"office":  2,
+	"billing": 3,
+	"other":   4,
+	"work":    5,
+}
+
+// AddressCategoryCode returns the numeric code for an AddressCategory label
+// (Home|Postal|Office|Billing|Other|Work) or a numeric string. Unknown/empty
+// labels fall back to Billing, the category `oo companies create` used.
+func AddressCategoryCode(category string) int {
+	s := strings.ToLower(strings.TrimSpace(category))
+	if s == "" {
+		return addressCategoryCodes["billing"]
+	}
+	if n, err := strconv.Atoi(s); err == nil {
+		if n >= 0 && n <= 5 {
+			return n
+		}
+		return addressCategoryCodes["billing"]
+	}
+	if n, ok := addressCategoryCodes[s]; ok {
+		return n
+	}
+	return addressCategoryCodes["billing"]
+}
+
+// ContactAddresses returns the postal address rows of a contact map.
+func ContactAddresses(contact map[string]any) []map[string]any {
+	if rows, ok := contact["addresses"].([]any); ok {
+		return mapsFromAnySlice(rows)
+	}
+	if rows, ok := contact["addresses"].([]map[string]any); ok {
+		return rows
+	}
+	return nil
+}
+
+// HasContactAddress reports whether a contact already has the given postal
+// address. street+city+zip+category identify it; comparison is normalized.
+func HasContactAddress(contact map[string]any, street, city, zip, category string) bool {
+	wantStreet, wantCity, wantZip := normalizeAddressPart(street), normalizeAddressPart(city), normalizeAddressPart(zip)
+	wantCat := AddressCategoryCode(category)
+	for _, row := range ContactAddresses(contact) {
+		if normalizeAddressPart(fmt.Sprint(row["street"])) != wantStreet {
+			continue
+		}
+		if normalizeAddressPart(fmt.Sprint(row["city"])) != wantCity {
+			continue
+		}
+		if normalizeAddressPart(fmt.Sprint(row["zip"])) != wantZip {
+			continue
+		}
+		if int(anyToFloat(row["category"])) != wantCat {
+			continue
+		}
+		return true
+	}
+	return false
+}
+
+func normalizeAddressPart(s string) string {
+	s = strings.ToLower(strings.TrimSpace(s))
+	return strings.Join(strings.Fields(s), " ")
+}
+
+func anyToFloat(v any) float64 {
+	switch n := v.(type) {
+	case float64:
+		return n
+	case int:
+		return float64(n)
+	case string:
+		f, _ := strconv.ParseFloat(strings.TrimSpace(n), 64)
+		return f
+	default:
+		return 0
+	}
+}
diff --git a/crm_address_test.go b/crm_address_test.go
new file mode 100644
index 0000000..4327eed
--- /dev/null
+++ b/crm_address_test.go
@@ -0,0 +1,42 @@
+package onlyoffice
+
+import "testing"
+
+func TestAddressCategoryCode(t *testing.T) {
+	cases := map[string]int{
+		"Home": 0, "Postal": 1, "Office": 2, "Billing": 3, "Other": 4, "Work": 5,
+		"billing": 3, " work ": 5, "3": 3, "5": 5,
+		"": 3, "nonsense": 3, "99": 3,
+	}
+	for in, want := range cases {
+		if got := AddressCategoryCode(in); got != want {
+			t.Errorf("AddressCategoryCode(%q) = %d, want %d", in, got, want)
+		}
+	}
+}
+
+func TestHasContactAddress(t *testing.T) {
+	contact := map[string]any{
+		"addresses": []any{
+			map[string]any{
+				"street": "Lubanas st. 125a-25", "city": "Riga",
+				"zip": "LV-1021", "country": "Latvia", "category": float64(3),
+			},
+		},
+	}
+	if !HasContactAddress(contact, "  Lubanas St. 125a-25 ", "riga", "lv-1021", "Billing") {
+		t.Error("want match (normalized, case-insensitive)")
+	}
+	if HasContactAddress(contact, "Lubanas st. 125a-25", "Riga", "LV-1021", "Work") {
+		t.Error("different category must not match")
+	}
+	if HasContactAddress(contact, "Lubanas st. 125a-25", "Riga", "00000", "Billing") {
+		t.Error("different zip must not match")
+	}
+	if HasContactAddress(map[string]any{}, "x", "y", "z", "Billing") {
+		t.Error("empty contact must not match")
+	}
+	if got := ContactAddresses(contact); len(got) != 1 {
+		t.Fatalf("ContactAddresses = %d rows", len(got))
+	}
+}
diff --git a/invoices.go b/invoices.go
index 55cfc34..1b1c8d7 100644
--- a/invoices.go
+++ b/invoices.go
@@ -443,21 +443,32 @@ func (c *Client) DeleteInvoiceItem(ctx context.Context, id string) (map[string]a
 	return c.deleteObject(ctx, fmt.Sprintf("/api/2.0/crm/invoiceitem/%s.json", url.PathEscape(id)))
 }
 
+// contactAddress is the JSON payload OO stores in a ContactInfo row of type
+// Address (ASC.Api.CRM.Wrappers.Address).
+type contactAddress struct {
+	Street  string `json:"street"`
+	City    string `json:"city"`
+	State   string `json:"state"`
+	Zip     string `json:"zip"`
+	Country string `json:"country"`
+}
+
 // AddContactAddress attaches a postal address to a contact.
-// category: Home|Postal|Office|Billing|Other|Work (or numeric string).
+// category: Home|Postal|Office|Billing|Other|Work.
+//
+// OO stores addresses as ContactInfo rows of infoType Address whose `data` is
+// the Address object as JSON (the dedicated /addressdata endpoint binds the
+// model from the body and is not accepted by all builds). The generic
+// /contact/{id}/data endpoint is the one `oo contacts info-add` uses.
 func (c *Client) AddContactAddress(ctx context.Context, contactID, street, city, state, zip, country, category string, isPrimary bool) (map[string]any, error) {
 	if category == "" {
 		category = "Billing"
 	}
-	fields := url.Values{}
-	fields.Set("street", street)
-	fields.Set("city", city)
-	fields.Set("state", state)
-	fields.Set("zip", zip)
-	fields.Set("country", country)
-	fields.Set("category", category)
-	fields.Set("isPrimary", strconv.FormatBool(isPrimary))
-	return c.postFormObject(ctx, fmt.Sprintf("/api/2.0/crm/contact/%s/address", url.PathEscape(contactID)), fields)
+	payload, err := json.Marshal(contactAddress{Street: street, City: city, State: state, Zip: zip, Country: country})
+	if err != nil {
+		return nil, err
+	}
+	return c.AddContactInfo(ctx, contactID, "Address", string(payload), category, isPrimary)
 }
 
 // UpdateCompany updates company name and optional about text.