diff --git a/apps/backoffice/src/app/features/certificate-designer/components/DesignerToolbar.tsx b/apps/backoffice/src/app/features/certificate-designer/components/DesignerToolbar.tsx
index 3a8296005..4ab644bc6 100644
--- a/apps/backoffice/src/app/features/certificate-designer/components/DesignerToolbar.tsx
+++ b/apps/backoffice/src/app/features/certificate-designer/components/DesignerToolbar.tsx
@@ -14,6 +14,8 @@ interface Props {
   onRankChange: (id: string | null) => void;
   /** Shown for context only; edited on Certificate Requirements → Behaviour. */
   validityMonths: number;
+  /** Non-null when the type is configured in days rather than months. */
+  validityDays?: number | null;
   canEdit: boolean;
   onNewVersion: () => void;
 }
@@ -27,6 +29,7 @@ export function DesignerToolbar({
   rankId,
   onRankChange,
   validityMonths,
+  validityDays,
   canEdit,
   onNewVersion,
 }: Props) {
@@ -75,11 +78,15 @@ export function DesignerToolbar({
       {typeId && (
         <Stack gap={2}>
           <Text size="xs" c="dimmed" fw={500}>
-            {t('designer.validityYears', 'Valid for (years)')}
+            {t('designer.validity', 'Valid for')}
           </Text>
           <Group gap={6} align="baseline">
             <Text size="sm" fw={600}>
-              {Number((validityMonths / 12).toFixed(2))}
+              {validityDays != null
+                ? t('designer.validityDays', '{{count}} days', { count: validityDays })
+                : t('designer.validityMonths', '{{count}} months', {
+                    count: validityMonths,
+                  })}
             </Text>
             <Text size="xs" c="dimmed">
               {t('designer.validityEditedOn', '— set on Certificate Requirements → Behaviour')}
diff --git a/apps/backoffice/src/app/features/certificate-designer/pages/CertificateDesignerPage.tsx b/apps/backoffice/src/app/features/certificate-designer/pages/CertificateDesignerPage.tsx
index 8f5597f49..b46d68689 100644
--- a/apps/backoffice/src/app/features/certificate-designer/pages/CertificateDesignerPage.tsx
+++ b/apps/backoffice/src/app/features/certificate-designer/pages/CertificateDesignerPage.tsx
@@ -163,6 +163,7 @@ export function CertificateDesignerPage() {
           draft.setSelectedId(null);
         }}
         validityMonths={selectedType?.validityMonths ?? 12}
+        validityDays={selectedType?.validityDays ?? null}
         canEdit={canEdit}
         onNewVersion={startNewVersion}
       />
diff --git a/apps/backoffice/src/app/features/certificate-requirements/components/BehaviorTab.tsx b/apps/backoffice/src/app/features/certificate-requirements/components/BehaviorTab.tsx
index 6acfd90b4..d756d1d38 100644
--- a/apps/backoffice/src/app/features/certificate-requirements/components/BehaviorTab.tsx
+++ b/apps/backoffice/src/app/features/certificate-requirements/components/BehaviorTab.tsx
@@ -38,6 +38,7 @@ interface Draft {
   minSeaTimeDays: number | null;
   capitalThreshold: number | null;
   validityMonths: number;
+  validityDays: number | null;
   renewalWindowDays: number;
   expiryReminderDays: number[];
   requiresOperatorMode: boolean;
@@ -66,6 +67,7 @@ function toDraft(licenseType: LicenseType): Draft {
         ? null
         : Number(licenseType.capitalThreshold),
     validityMonths: licenseType.validityMonths ?? 12,
+    validityDays: licenseType.validityDays ?? null,
     renewalWindowDays: licenseType.renewalWindowDays ?? 60,
     expiryReminderDays: licenseType.expiryReminderDays ?? [60, 30, 7],
     requiresOperatorMode: licenseType.requiresOperatorMode ?? true,
@@ -266,25 +268,52 @@ export function BehaviorTab({ licenseType }: { licenseType: LicenseType }) {
       </Section>
 
       <Section title={t('certReq.behavior.renewal', 'Validity and renewal')}>
-        {/* Stored in months, edited in years: a licence term is a number of
-            years to everyone who works with one. Half-years stay expressible. */}
-        <NumberInput
-          label={t('certReq.behavior.validityYears', 'Valid for (years)')}
-          description={t(
-            'certReq.behavior.validityHint',
-            'Applied when a licence is issued. Licences already issued keep the expiry date they were given.',
-          )}
-          value={Number((draft.validityMonths / 12).toFixed(2))}
-          onChange={(v) =>
-            set('validityMonths', Math.round(Number(v || 0) * 12) || draft.validityMonths)
-          }
-          min={0.5}
-          max={20}
-          step={0.5}
-          decimalScale={1}
-          allowNegative={false}
-          disabled={!canEdit}
-        />
+        {/* Amount + unit rather than a years box that silently divides by 12:
+            the seed says `validityMonths: 12` and this now says "12 Months",
+            so the two read the same. Months advance the calendar (issued on
+            the 31st, expires on the 31st); days are for terms shorter than a
+            month can express. */}
+        <Group align="flex-end" gap="sm" wrap="nowrap">
+          <NumberInput
+            label={t('certReq.behavior.validity', 'Valid for')}
+            description={t(
+              'certReq.behavior.validityHint',
+              'Applied when a licence is issued. Licences already issued keep the expiry date they were given.',
+            )}
+            value={draft.validityDays ?? draft.validityMonths}
+            onChange={(v) => {
+              const next = typeof v === 'number' ? v : 0;
+              if (!next) return;
+              if (draft.validityDays !== null) set('validityDays', next);
+              else set('validityMonths', next);
+            }}
+            // Matches the server's ranges, so the box cannot offer a value the
+            // save would reject: 1–3650 days, or 6–240 months.
+            min={draft.validityDays !== null ? 1 : 6}
+            max={draft.validityDays !== null ? 3650 : 240}
+            allowNegative={false}
+            disabled={!canEdit}
+            flex={1}
+          />
+          <Select
+            aria-label={t('certReq.behavior.validityUnit', 'Validity unit')}
+            data={[
+              { value: 'MONTHS', label: t('certReq.behavior.unitMonths', 'Months') },
+              { value: 'DAYS', label: t('certReq.behavior.unitDays', 'Days') },
+            ]}
+            value={draft.validityDays !== null ? 'DAYS' : 'MONTHS'}
+            onChange={(unit) => {
+              // Switching unit is a change of policy, not a conversion: 12
+              // calendar months is not 365 days, so carry no arithmetic across
+              // and let the administrator state the new term outright.
+              if (unit === 'DAYS') set('validityDays', draft.validityDays ?? 90);
+              else set('validityDays', null);
+            }}
+            allowDeselect={false}
+            disabled={!canEdit}
+            w={130}
+          />
+        </Group>
 
         <NumberInput
           label={t('certReq.behavior.renewalWindow', 'Renewal opens (days before expiry)')}
diff --git a/apps/backoffice/src/app/i18n/locales/am.ts b/apps/backoffice/src/app/i18n/locales/am.ts
index d83b5d451..f3b3abfac 100644
--- a/apps/backoffice/src/app/i18n/locales/am.ts
+++ b/apps/backoffice/src/app/i18n/locales/am.ts
@@ -1225,7 +1225,11 @@ export const am: Translations = {
     title: "የምስክር ወረቀት ንድፍ",
     subtitle: "ለፈቃድ ባለቤቶች የሚሰጠውን የምስክር ወረቀት ይንደፉ።",
     licenceType: "የፈቃድ ዓይነት",
-    validityYears: "የሚቆይበት (ዓመታት)",
+    validity: "የሚቆይበት",
+    validityMonths_one: "{{count}} ወር",
+    validityMonths_other: "{{count}} ወራት",
+    validityDays_one: "{{count}} ቀን",
+    validityDays_other: "{{count}} ቀናት",
     validityEditedOn: "— በምስክር ወረቀት መስፈርቶች → ባህሪ ውስጥ ይዘጋጃል",
     newVersion: "አዲስ ስሪት",
     versions: "ስሪቶች",
@@ -1299,7 +1303,10 @@ export const am: Translations = {
       capitalOn: "አነስተኛ የተከፈለ ካፒታል ይጠየቅ",
       capitalHint:
         "ኃላፊው ከዚህ እኩል ወይም በላይ የሆነ ካፒታል እስኪያረጋግጥ ድረስ ማጽደቅ አይችልም። ለአዲሶቹ ብቻ ሳይሆን ቀደም ብለው በወረፋ ላይ ላሉ ማመልከቻዎችም ይሠራል።",
-      validityYears: "የሚቆይበት (ዓመታት)",
+      validity: "የሚቆይበት",
+      validityUnit: "የሚቆይበት መለኪያ",
+      unitMonths: "ወራት",
+      unitDays: "ቀናት",
       validityHint:
         "ፈቃድ ሲሰጥ ተግባራዊ ይሆናል። ቀደም ብለው የተሰጡ ፈቃዶች የተሰጣቸውን የማብቂያ ቀን ይይዛሉ።",
       requiresSeafarer: "የጸና የመርከበኛ ምዝገባ ያስፈልገዋል",
diff --git a/apps/backoffice/src/app/i18n/locales/en.ts b/apps/backoffice/src/app/i18n/locales/en.ts
index 8279081ec..c09503dbf 100644
--- a/apps/backoffice/src/app/i18n/locales/en.ts
+++ b/apps/backoffice/src/app/i18n/locales/en.ts
@@ -1231,7 +1231,11 @@ export const en = {
     title: 'Certificate designer',
     subtitle: 'Design the certificate issued to licence holders.',
     licenceType: 'Licence type',
-    validityYears: 'Valid for (years)',
+    validity: 'Valid for',
+    validityMonths_one: '{{count}} month',
+    validityMonths_other: '{{count}} months',
+    validityDays_one: '{{count}} day',
+    validityDays_other: '{{count}} days',
     validityEditedOn: '— set on Certificate Requirements → Behaviour',
     newVersion: 'New version',
     versions: 'Versions',
@@ -1304,7 +1308,10 @@ export const en = {
       capitalOn: 'Require a minimum paid-up capital',
       capitalHint:
         'An officer cannot approve until they have verified capital at or above this. Applies to applications already in the queue, not just new ones.',
-      validityYears: 'Valid for (years)',
+      validity: 'Valid for',
+      validityUnit: 'Validity unit',
+      unitMonths: 'Months',
+      unitDays: 'Days',
       validityHint:
         'Applied when a licence is issued. Licences already issued keep the expiry date they were given.',
       requiresSeafarer: 'Requires an active seafarer registration',
diff --git a/libs/api/src/lib/features/licensing/licensing-api.ts b/libs/api/src/lib/features/licensing/licensing-api.ts
index e1a56677a..f0dcf3534 100644
--- a/libs/api/src/lib/features/licensing/licensing-api.ts
+++ b/libs/api/src/lib/features/licensing/licensing-api.ts
@@ -227,6 +227,7 @@ export const licensingApi = baseApi
           requiresValidMedical?: boolean;
           minSeaTimeDays?: number | null;
           validityMonths?: number;
+          validityDays?: number | null;
           capitalThreshold?: number | null;
           renewalWindowDays?: number;
           expiryReminderDays?: number[];
diff --git a/libs/api/src/lib/features/licensing/licensing.types.ts b/libs/api/src/lib/features/licensing/licensing.types.ts
index 13cbfe818..058211621 100644
--- a/libs/api/src/lib/features/licensing/licensing.types.ts
+++ b/libs/api/src/lib/features/licensing/licensing.types.ts
@@ -187,6 +187,11 @@ export interface LicenseType {
   feeCurrency: string;
   capitalThreshold: string | number | null;
   validityMonths: number;
+  /**
+   * A term in days instead of months, for licences shorter than a month can
+   * express. Wins over `validityMonths` when set; null keeps calendar months.
+   */
+  validityDays?: number | null;
   /**
    * Target turnaround in hours. Null means this type is not tracked against
    * an SLA, which the grid renders as "—" rather than as instantly overdue.