diff --git a/CLAUDE.md b/CLAUDE.md
index 9d07e29..dd7598f 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -146,6 +146,13 @@ Variety (品種マスタ)
    - `display_order` (リスト表示時の順序)
    - マイグレーション0004で追加
 
+5. **年度管理の設計方針**（⚠️ Phase 2 で必ず参照）:
+   - **作付け計画**: 年度セレクタで独立して来年度も選べる。選んだ年度はlocalStorageに保存して維持
+   - **過去年度**: 「参照モード」として視覚的に区別（背景色・バナー）
+   - **Phase 2 の栽培管理・販売管理**: グローバル作業年度を導入し、基本は今年度に従う
+   - **栽培記録・作業日誌**: 日付中心設計、年度は日付から自動算出
+   - 参考: ソリマチ農業簿記の年度管理方式（明示的に年度を選択、変更するまで固定）
+
 ---
 
 ## 🔑 重要な制約・ルール
diff --git a/frontend/src/app/allocation/page.tsx b/frontend/src/app/allocation/page.tsx
index d8d0767..1ff2fca 100644
--- a/frontend/src/app/allocation/page.tsx
+++ b/frontend/src/app/allocation/page.tsx
@@ -23,7 +23,13 @@ export default function AllocationPage() {
   const [fields, setFields] = useState<Field[]>([]);
   const [crops, setCrops] = useState<Crop[]>([]);
   const [plans, setPlans] = useState<Plan[]>([]);
-  const [year, setYear] = useState<number>(2025);
+  const [year, setYear] = useState<number>(() => {
+    if (typeof window !== 'undefined') {
+      const saved = localStorage.getItem('allocationYear');
+      if (saved) return parseInt(saved);
+    }
+    return new Date().getFullYear();
+  });
   const [loading, setLoading] = useState(true);
   const [saving, setSaving] = useState<number | null>(null);
   const [showSidebar, setShowSidebar] = useState(true);
@@ -44,9 +50,13 @@ export default function AllocationPage() {
   const [filterUnassigned, setFilterUnassigned] = useState(false);
 
   useEffect(() => {
+    localStorage.setItem('allocationYear', String(year));
     fetchData();
   }, [year]);
 
+  const currentYear = new Date().getFullYear();
+  const isPastYear = year < currentYear;
+
   const fetchData = async (background = false) => {
     if (!background) setLoading(true);
     try {
@@ -540,7 +550,9 @@ export default function AllocationPage() {
         <div className="flex-1 min-w-0 p-4 lg:p-0">
           <div className="max-w-7xl mx-auto">
             <div className="mb-6 flex flex-col sm:flex-row sm:items-center justify-between gap-4">
-              <h1 className="text-2xl font-bold text-gray-900">作付け計画</h1>
+              <h1 className="text-2xl font-bold text-gray-900">
+                作付け計画 <span className="text-green-700">{year}年度</span>
+              </h1>
 
               {/* スマホ用集計ボタン */}
               <button
@@ -569,11 +581,11 @@ export default function AllocationPage() {
                   id="year"
                   value={year}
                   onChange={(e) => setYear(parseInt(e.target.value))}
-                  className="px-3 py-2 border border-gray-300 rounded-md focus:outline-none focus:ring-2 focus:ring-green-500"
+                  className="px-3 py-2 border border-gray-300 rounded-md focus:outline-none focus:ring-2 focus:ring-green-500 font-semibold"
                 >
-                  <option value={2025}>2025年</option>
-                  <option value={2026}>2026年</option>
-                  <option value={2027}>2027年</option>
+                  {Array.from({ length: 5 }, (_, i) => new Date().getFullYear() - 2 + i).map((y) => (
+                    <option key={y} value={y}>{y}年</option>
+                  ))}
                 </select>
 
                 <button
@@ -649,6 +661,20 @@ export default function AllocationPage() {
               </div>
             ) : (
               <>
+                {isPastYear && (
+                  <div className="mb-4 p-3 bg-amber-50 border border-amber-300 rounded-md flex items-center justify-between">
+                    <p className="text-sm text-amber-800 font-medium">
+                      {year}年度のデータを参照中（過去年度）
+                    </p>
+                    <button
+                      onClick={() => setYear(currentYear)}
+                      className="text-sm text-amber-700 underline hover:text-amber-900"
+                    >
+                      {currentYear}年度に戻る
+                    </button>
+                  </div>
+                )}
+
                 <div className="mb-4 p-3 bg-blue-50 border border-blue-200 rounded-md">
                   <p className="text-sm text-blue-800">
                     💡 グループ名を入力して「グループ順」で並び替え、「↑」「↓」ボタンで順序を変更できます
@@ -699,7 +725,7 @@ export default function AllocationPage() {
                   </div>
                 )}
 
-                <div className="bg-white rounded-lg shadow overflow-hidden">
+                <div className={`rounded-lg shadow overflow-hidden ${isPastYear ? 'bg-amber-50/50 ring-1 ring-amber-200' : 'bg-white'}`}>
                   <div className="overflow-x-auto">
                     <table className="min-w-full divide-y divide-gray-200">
                       <thead className="bg-gray-50">
diff --git a/frontend/src/app/reports/page.tsx b/frontend/src/app/reports/page.tsx
index 925739d..442f230 100644
--- a/frontend/src/app/reports/page.tsx
+++ b/frontend/src/app/reports/page.tsx
@@ -26,7 +26,7 @@ const previewPdf = async (url: string) => {
 };
 
 export default function ReportsPage() {
-  const [year, setYear] = useState<number>(2025);
+  const [year, setYear] = useState<number>(new Date().getFullYear());
   const [busy, setBusy] = useState<string | null>(null);
 
   const handleAction = async (action: 'download' | 'preview', type: 'kyosai' | 'chusankan') => {
@@ -67,9 +67,9 @@ export default function ReportsPage() {
               onChange={(e) => setYear(parseInt(e.target.value))}
               className="px-3 py-2 border border-gray-300 rounded-md focus:outline-none focus:ring-2 focus:ring-green-500 w-full max-w-xs"
             >
-              <option value={2025}>2025年</option>
-              <option value={2026}>2026年</option>
-              <option value={2027}>2027年</option>
+              {Array.from({ length: 5 }, (_, i) => new Date().getFullYear() - 2 + i).map((y) => (
+                <option key={y} value={y}>{y}年</option>
+              ))}
             </select>
           </div>