<!--
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WordPress カスタムHTMLブロック用コード
ふるさと納税控除額シミュレーター（簡易版・公的機関版）
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【機能】年収・家族構成から控除上限額を計算（グラフ表示を除く）
【セキュリティ】✅ ブラウザ内完結 ✅ 通信ゼロ ✅ 外部CDN依存なし
【利用規約】無償・無保証、税務判断は自己責任
【特徴】Chart.js不使用・完全スタンドアロン・アクセシビリティ対応
【外部依存】なし
【データソース】総務省ふるさと納税ポータル、国税庁タックスアンサー
【計算式】所得税・住民税の控除額から上限額を逆算
================================================
-->

<!-- MSIM:STYLE-START -->
<style>
.furusato-simulator{box-sizing:border-box;max-width:800px;margin:0 auto;padding:20px;font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"Helvetica Neue",Arial,sans-serif;background:#fff;border-radius:8px;box-shadow:0 2px 8px rgba(0,0,0,0.1)}
.furusato-simulator *{box-sizing:border-box}
.furusato-simulator h1{font-size:24px;font-weight:700;text-align:center;margin:0 0 10px;color:#333}
.furusato-simulator .subtitle{font-size:14px;color:#666;text-align:center;margin:0 0 20px;line-height:1.6}
.furusato-simulator .input-section{background:#f8f9fa;padding:20px;border-radius:8px;margin-bottom:20px}
.furusato-simulator .input-group{margin-bottom:20px}
.furusato-simulator .input-group:last-child{margin-bottom:0}
.furusato-simulator label{display:block;font-size:14px;font-weight:600;margin-bottom:8px;color:#333}
.furusato-simulator input[type="range"]{width:100%;height:6px;border-radius:3px;background:#ddd;outline:none;-webkit-appearance:none;appearance:none}
.furusato-simulator input[type="range"]::-webkit-slider-thumb{-webkit-appearance:none;appearance:none;width:18px;height:18px;border-radius:50%;background:#4a90e2;cursor:pointer}
.furusato-simulator input[type="range"]::-moz-range-thumb{width:18px;height:18px;border-radius:50%;background:#4a90e2;cursor:pointer;border:none}
.furusato-simulator input[type="number"]{width:100%;padding:10px;font-size:14px;border:1px solid #ddd;border-radius:4px}
.furusato-simulator select{width:100%;padding:10px;font-size:14px;border:1px solid #ddd;border-radius:4px;background:#fff}
.furusato-simulator .value-display{display:inline-block;min-width:120px;padding:6px 12px;background:#fff;border:1px solid #ddd;border-radius:4px;font-size:14px;font-weight:600;color:#4a90e2;text-align:right}
.furusato-simulator .result-section{background:#e8f4f8;padding:20px;border-radius:8px;margin-bottom:20px}
.furusato-simulator .result-item{display:flex;justify-content:space-between;align-items:center;padding:12px 0;border-bottom:1px solid #d0e8f0}
.furusato-simulator .result-item:last-child{border-bottom:none}
.furusato-simulator .result-label{font-size:14px;font-weight:600;color:#333}
.furusato-simulator .result-value{font-size:20px;font-weight:700;color:#4a90e2}
.furusato-simulator .result-value.highlight{font-size:24px;color:#e74c3c}
.furusato-simulator .breakdown-section{margin-bottom:20px}
.furusato-simulator .breakdown-section table{width:100%;border-collapse:collapse;font-size:14px}
.furusato-simulator .breakdown-section th{background:#4a90e2;color:#fff;padding:10px;text-align:left;font-weight:600}
.furusato-simulator .breakdown-section td{padding:10px;border-bottom:1px solid #ddd}
.furusato-simulator .breakdown-section td.text-right{text-align:right}
.furusato-simulator .breakdown-section tr:last-child td{border-bottom:none;font-weight:700}
.furusato-simulator .info-section{background:#fff3cd;padding:15px;border-radius:8px;border-left:4px solid #ffc107;margin-bottom:20px}
.furusato-simulator .info-section p{margin:0;font-size:13px;color:#856404;line-height:1.6}
.furusato-simulator .disclaimer-section{background:#f8f9fa;padding:15px;border-radius:8px;font-size:12px;color:#666;line-height:1.6;margin-bottom:20px}
.furusato-simulator .disclaimer-section p{margin:0 0 10px}
.furusato-simulator .disclaimer-section p:last-child{margin:0}
@media(max-width:600px){
.furusato-simulator{padding:15px}
.furusato-simulator h1{font-size:20px}
.furusato-simulator .result-value{font-size:18px}
.furusato-simulator .result-value.highlight{font-size:22px}
.furusato-simulator .breakdown-section table{font-size:12px}
.furusato-simulator .breakdown-section th,.furusato-simulator .breakdown-section td{padding:8px}
}
</style>
<!-- MSIM:STYLE-END -->

<!-- MSIM:HTML-START -->
<div class="furusato-simulator" data-tool="furusato-tax" data-version="1.0.0">
<h1>ふるさと納税控除額シミュレーター</h1>
<p class="subtitle">年収・家族構成から実質2,000円で寄付できる控除上限額を計算</p>

<div class="input-section">
<div class="input-group">
<label>年収（給与収入）: <span class="value-display" data-ms-income-display>¥5,000,000</span></label>
<input type="range" data-ms-income min="2000000" max="30000000" step="100000" value="5000000">
</div>

<div class="input-group">
<label>家族構成</label>
<select data-ms-family>
<option value="single">独身・共働き</option>
<option value="married">夫婦（配偶者控除あり）</option>
<option value="married-child1-high">夫婦+子1人（高校生）</option>
<option value="married-child1-univ">夫婦+子1人（大学生）</option>
<option value="married-child2">夫婦+子2人（大学生+高校生）</option>
</select>
</div>

<div class="input-group">
<label>社会保険料（年額）: <span class="value-display" data-ms-social-display>¥750,000</span></label>
<input type="range" data-ms-social min="0" max="5000000" step="10000" value="750000">
<p style="font-size:12px;color:#666;margin:5px 0 0">※ デフォルトは年収の15%で自動計算されます</p>
</div>

<div class="input-group">
<label>その他控除（医療費控除・生命保険料控除等）</label>
<input type="number" data-ms-other-deduction min="0" step="10000" value="0" placeholder="0">
</div>
</div>

<div class="result-section">
<div class="result-item">
<span class="result-label">控除上限額（目安）</span>
<span class="result-value highlight" data-ms-limit>¥0</span>
</div>
<div class="result-item">
<span class="result-label">自己負担額</span>
<span class="result-value" data-ms-self-burden>¥2,000</span>
</div>
<div class="result-item">
<span class="result-label">節税効果（目安）</span>
<span class="result-value" data-ms-tax-saving>¥0</span>
</div>
</div>

<div class="breakdown-section">
<table>
<thead>
<tr>
<th>年収</th>
<th style="text-align:right">控除上限額（目安）</th>
</tr>
</thead>
<tbody data-ms-breakdown-table></tbody>
</table>
</div>

<div class="info-section">
<p><strong>💡 ポイント</strong><br>控除上限額までの寄付なら、自己負担は実質2,000円のみ。<br>上限を超えた分は控除されず、全額自己負担となります。</p>
</div>

<div class="disclaimer-section">
<p><strong>⚠️ 注意事項</strong></p>
<p>・このシミュレーターは簡易計算による目安です。正確な控除額は税務署にご確認ください。</p>
<p>・給与所得者を想定しており、事業所得・不動産所得等は考慮していません。</p>
<p>・住宅ローン控除等の税額控除は計算に含まれていません。</p>
<p>・計算結果に基づく損害について、当サイトは一切の責任を負いません。</p>
</div>

<div style="text-align:right;margin-top:30px;color:#999;font-size:12px">
Powered by <a href="https://minna-calc.com/" target="_blank" rel="noopener" style="color:#4a90e2;text-decoration:none">みんなのシミュレーター</a>
</div>
</div>
<!-- MSIM:HTML-END -->

<!-- MSIM:JS-START -->
<script>
(()=>{
"use strict";
const TOOL="furusato-tax";
const ROOT_SELECTOR=`.furusato-simulator[data-tool="${TOOL}"]`;
const fmt=new Intl.NumberFormat("ja-JP",{style:"currency",currency:"JPY",minimumFractionDigits:0,maximumFractionDigits:0});

const registerInit=handler=>{
let pending=false;
const schedule=()=>{
if(pending)return;
pending=true;
requestAnimationFrame(()=>{
pending=false;
handler();
});
};
queueMicrotask(schedule);
if(document.readyState!=="loading")schedule();
document.addEventListener("DOMContentLoaded",schedule,{passive:true});
window.addEventListener("load",schedule,{passive:true});
document.addEventListener("readystatechange",()=>{
if(document.readyState==="interactive"||document.readyState==="complete"){
schedule();
}
},{passive:true});
new MutationObserver(schedule).observe(document.body,{childList:true,subtree:true});
};

function boot(root){
if(root.dataset.msimInitialized==="true")return;
root.dataset.msimInitialized="true";
const q=sel=>root.querySelector(sel);
const els={
income:q('[data-ms-income]'),
incomeDisplay:q('[data-ms-income-display]'),
family:q('[data-ms-family]'),
social:q('[data-ms-social]'),
socialDisplay:q('[data-ms-social-display]'),
otherDeduction:q('[data-ms-other-deduction]'),
limit:q('[data-ms-limit]'),
selfBurden:q('[data-ms-self-burden]'),
taxSaving:q('[data-ms-tax-saving]'),
breakdownTable:q('[data-ms-breakdown-table]')
};

// 給与所得控除（令和2年以降）
function salaryDeduction(income){
if(income<=1625000)return 550000;
if(income<=1800000)return income*0.4-100000;
if(income<=3600000)return income*0.3+80000;
if(income<=6600000)return income*0.2+440000;
if(income<=8500000)return income*0.1+1100000;
return 1950000;
}

// 家族構成による所得控除
function familyDeduction(family){
const deductions={
single:0,
married:380000,
"married-child1-high":760000,
"married-child1-univ":1010000,
"married-child2":1390000
};
return deductions[family]||0;
}

// 所得税率（復興特別所得税込み）
function incomeTaxRate(taxableIncome){
if(taxableIncome<=1950000)return 0.05*1.021;
if(taxableIncome<=3300000)return 0.10*1.021;
if(taxableIncome<=6950000)return 0.20*1.021;
if(taxableIncome<=9000000)return 0.23*1.021;
if(taxableIncome<=18000000)return 0.33*1.021;
if(taxableIncome<=40000000)return 0.40*1.021;
return 0.45*1.021;
}

function calculate(){
const income=parseInt(els.income.value);
const family=els.family.value;
const social=parseInt(els.social.value);
const otherDeduction=parseInt(els.otherDeduction.value)||0;

// 給与所得
const salaryIncome=income-salaryDeduction(income);

// 課税所得
const basicDeduction=480000;
const totalDeduction=basicDeduction+familyDeduction(family)+social+otherDeduction;
const taxableIncome=Math.max(0,salaryIncome-totalDeduction);

// 所得税率
const taxRate=incomeTaxRate(taxableIncome);

// 住民税所得割額（10%）
const residentTaxIncome=Math.max(0,salaryIncome-(basicDeduction-50000)-familyDeduction(family)-social-otherDeduction);
const residentTaxAmount=residentTaxIncome*0.1;

// 控除上限額（簡易計算式）
const limit=Math.floor((residentTaxAmount*0.2)/(1-0.1-taxRate)+2000);

// 節税効果（控除上限額 - 自己負担2,000円）
const taxSaving=Math.max(0,limit-2000);

// 年収別目安表（200万〜3000万を20分割）
const breakdownRows=[];
for(let i=2000000;i<=30000000;i+=1400000){
const salInc=i-salaryDeduction(i);
const taxInc=Math.max(0,salInc-basicDeduction-familyDeduction(family)-(i*0.15)-otherDeduction);
const rate=incomeTaxRate(taxInc);
const resTaxInc=Math.max(0,salInc-(basicDeduction-50000)-familyDeduction(family)-(i*0.15)-otherDeduction);
const resTaxAmt=resTaxInc*0.1;
const lim=Math.floor((resTaxAmt*0.2)/(1-0.1-rate)+2000);
breakdownRows.push({
incomeLabel:`${(i/10000).toFixed(0)}万円`,
limitAmount:lim
});
}

return{limit,taxSaving,breakdownRows};
}

function render(){
const result=calculate();
els.incomeDisplay.textContent=fmt.format(parseInt(els.income.value));
els.socialDisplay.textContent=fmt.format(parseInt(els.social.value));
els.limit.textContent=fmt.format(result.limit);
els.selfBurden.textContent="¥2,000";
els.taxSaving.textContent=fmt.format(result.taxSaving);

if(els.breakdownTable){
const rows=result.breakdownRows.map(item=>
`<tr><td>${item.incomeLabel}</td><td class="text-right">${fmt.format(item.limitAmount)}</td></tr>`
);
els.breakdownTable.innerHTML=rows.join("");
}
}

// 年収変更時に社会保険料を自動計算（15%）
els.income.addEventListener("input",()=>{
const income=parseInt(els.income.value);
els.social.value=Math.floor(income*0.15);
els.socialDisplay.textContent=fmt.format(els.social.value);
render();
},{passive:true});

els.family.addEventListener("input",render,{passive:true});
els.social.addEventListener("input",()=>{
els.socialDisplay.textContent=fmt.format(parseInt(els.social.value));
render();
},{passive:true});
els.otherDeduction.addEventListener("input",render,{passive:true});

render();
}

function init(){
document.querySelectorAll(ROOT_SELECTOR).forEach(boot);
}

registerInit(init);
})();
</script>
<!-- MSIM:JS-END -->