diff --git a/backend/alembic/versions/7c8d9e0f1a2b_add_annex30_duration_days.py b/backend/alembic/versions/7c8d9e0f1a2b_add_annex30_duration_days.py
new file mode 100644
index 00000000..ec565c31
--- /dev/null
+++ b/backend/alembic/versions/7c8d9e0f1a2b_add_annex30_duration_days.py
@@ -0,0 +1,29 @@
+"""add annex30_duration_days to company_certification
+
+Revision ID: 7c8d9e0f1a2b
+Revises: c8d9e0f1a2b3
+Create Date: 2026-04-24 16:50:00.000000
+
+"""
+
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = '7c8d9e0f1a2b'
+down_revision = 'c8d9e0f1a2b3'
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.add_column(
+        "company_certification",
+        sa.Column("annex30_duration_days", sa.Integer(), nullable=True),
+        schema="a76",
+    )
+
+
+def downgrade() -> None:
+    op.drop_column("company_certification", "annex30_duration_days", schema="a76")
diff --git a/backend/api/v1/modules/a76/general_catalogs/company/dto.py b/backend/api/v1/modules/a76/general_catalogs/company/dto.py
index 97421872..39f71b25 100644
--- a/backend/api/v1/modules/a76/general_catalogs/company/dto.py
+++ b/backend/api/v1/modules/a76/general_catalogs/company/dto.py
@@ -99,6 +99,7 @@ class CompanyCreateDTO(BaseModel):
     annex30_certification_date: Optional[date] = None
     annex30_certification_number: Optional[str] = Field(None, max_length=50)
     annex30_modality: Optional[str] = Field(None, max_length=3)
+    annex30_duration_days: Optional[int] = Field(None, description="Modality duration in days")
     annex30_company_type: Optional[str] = Field(None, max_length=50)
     annex30_renewal_date: Optional[date] = None
     annex30_final_certification_date: Optional[date] = None
@@ -328,6 +329,7 @@ class CompanyResponseDTO(BaseModel):
     annex30_certification_date: Optional[date] = None
     annex30_certification_number: Optional[str] = None
     annex30_modality: Optional[str] = None
+    annex30_duration_days: Optional[int] = None
     annex30_company_type: Optional[str] = None
     annex30_renewal_date: Optional[date] = None
     annex30_final_certification_date: Optional[date] = None
diff --git a/backend/api/v1/modules/a76/general_catalogs/company/service.py b/backend/api/v1/modules/a76/general_catalogs/company/service.py
index 962292d8..0c55a9d5 100644
--- a/backend/api/v1/modules/a76/general_catalogs/company/service.py
+++ b/backend/api/v1/modules/a76/general_catalogs/company/service.py
@@ -136,7 +136,7 @@ class CompanyService:
             "is_certified_company", "certified_company_registration",
             "certified_company_start_date", "certified_company_end_date",
             "annex30_certification_date", "annex30_certification_number",
-            "annex30_modality", "annex30_company_type", "annex30_renewal_date",
+            "annex30_modality", "annex30_duration_days", "annex30_company_type", "annex30_renewal_date",
             "annex30_final_certification_date", "is_seciit_company", "is_oea_company", "ctpat_svi",
             "trusted_exporter_number", "neec_company"
         ]
@@ -251,7 +251,7 @@ class CompanyService:
                 "is_certified_company", "certified_company_registration",
                 "certified_company_start_date", "certified_company_end_date",
                 "annex30_certification_date", "annex30_certification_number",
-                "annex30_modality", "annex30_company_type", "annex30_renewal_date",
+                "annex30_modality", "annex30_duration_days", "annex30_company_type", "annex30_renewal_date",
                 "annex30_final_certification_date", "is_seciit_company", "is_oea_company", "ctpat_svi",
                 "trusted_exporter_number", "neec_company"
             ]
diff --git a/backend/api/v1/modules/a76/general_catalogs/company/submodels/certification.py b/backend/api/v1/modules/a76/general_catalogs/company/submodels/certification.py
index ee70040a..7ca28af4 100644
--- a/backend/api/v1/modules/a76/general_catalogs/company/submodels/certification.py
+++ b/backend/api/v1/modules/a76/general_catalogs/company/submodels/certification.py
@@ -37,6 +37,7 @@ class CompanyCertification(Base, TimestampMixin):
     annex30_certification_date: Mapped[Optional[date]] = mapped_column(Date)
     annex30_certification_number: Mapped[Optional[str]] = mapped_column(String(50))
     annex30_modality: Mapped[Optional[str]] = mapped_column(String(3))
+    annex30_duration_days: Mapped[Optional[int]] = mapped_column(Integer)
     annex30_company_type: Mapped[Optional[str]] = mapped_column(String(50))
     annex30_renewal_date: Mapped[Optional[date]] = mapped_column(Date)
     annex30_final_certification_date: Mapped[Optional[date]] = mapped_column(Date)
diff --git a/frontend/src/routes/dashboard/general_catalogs/company_information/edit/[[id]]/+page.svelte b/frontend/src/routes/dashboard/general_catalogs/company_information/edit/[[id]]/+page.svelte
index b2faeef1..61b19a4d 100644
--- a/frontend/src/routes/dashboard/general_catalogs/company_information/edit/[[id]]/+page.svelte
+++ b/frontend/src/routes/dashboard/general_catalogs/company_information/edit/[[id]]/+page.svelte
@@ -112,6 +112,7 @@
 		annex30_certification_date: '',
 		annex30_certification_number: '',
 		annex30_modality: '',
+		annex30_duration_days: 0,
 		annex30_company_type: '',
 		annex30_renewal_date: '',
 		annex30_final_certification_date: '',
@@ -300,6 +301,7 @@
 					annex30_certification_date: toInputDate(item.annex30_certification_date),
 					annex30_certification_number: item.annex30_certification_number || '',
 					annex30_modality: item.annex30_modality || '',
+					annex30_duration_days: item.annex30_duration_days || 0,
 					annex30_company_type: item.annex30_company_type || '',
 					annex30_renewal_date: toInputDate(item.annex30_renewal_date),
 					annex30_final_certification_date: toInputDate(item.annex30_final_certification_date),
@@ -531,6 +533,36 @@
 			loading = false;
 		}
 	}
+	
+	// Auto-cálculo de duración y fecha de renovación del Anexo 30
+	$effect(() => {
+		const modality = formData.annex30_modality;
+		const certDateStr = formData.annex30_certification_date;
+
+		// 1. Mapear modalidad a días
+		const modalityDaysMap: Record<string, number> = {
+			'A': 365,
+			'AA': 730,
+			'AAA': 1095
+		};
+
+		if (modality && modalityDaysMap[modality]) {
+			formData.annex30_duration_days = modalityDaysMap[modality];
+		} else if (!modality) {
+			formData.annex30_duration_days = 0;
+		}
+
+		// 2. Calcular fecha de renovación
+		if (certDateStr && formData.annex30_duration_days > 0) {
+			// Usamos el formato ISO para evitar problemas de zona horaria al crear el objeto Date
+			const certDate = new Date(certDateStr + 'T00:00:00');
+			if (!isNaN(certDate.getTime())) {
+				const renewalDate = new Date(certDate);
+				renewalDate.setDate(certDate.getDate() + formData.annex30_duration_days);
+				formData.annex30_renewal_date = renewalDate.toISOString().split('T')[0];
+			}
+		}
+	});
 
 	async function handleSubmit() {
 		error = null;
@@ -598,6 +630,7 @@
 				annex30_certification_date: toDbDate(formData.annex30_certification_date),
 				annex30_certification_number: clean(formData.annex30_certification_number),
 				annex30_modality: clean(formData.annex30_modality),
+				annex30_duration_days: Number(formData.annex30_duration_days) || 0,
 				annex30_company_type: clean(formData.annex30_company_type),
 				annex30_renewal_date: toDbDate(formData.annex30_renewal_date),
 				annex30_final_certification_date: toDbDate(formData.annex30_final_certification_date),
@@ -1035,6 +1068,16 @@
 											<option value="AAA">AAA</option>
 										</select>
 									</div>
+									<div class="grid gap-2">
+										<Label for="a31_duration">Duración Modalidad (Días)</Label>
+										<Input
+											id="a31_duration"
+											type="number"
+											bind:value={formData.annex30_duration_days}
+											readonly
+											class="bg-muted"
+										/>
+									</div>
 									<div class="grid gap-2">
 										<Label for="a31_type">Tipo de Empresa Anexo 30</Label>
 										<select