Japanese Invoice Helper

An Obsidian plugin for writing Japanese invoices (適格請求書) in Markdown. It calculates consumption tax per rate, withholding tax (源泉徴収) and payment due dates, and renders a printable invoice you can export to PDF.

日本語の説明はこちら

Features

• Invoice in a note — metadata in frontmatter, line items in a Markdown table, and an invoice code block that renders the finished document
• Correct tax arithmetic — consumption tax summarized per rate (10% / 8% reduced / exempt) and rounded once per rate per invoice, as the qualified-invoice rules require; rounding mode is configurable
• Withholding tax — 10.21% up to ¥1,000,000 and 20.42% above, on the pre-tax or tax-inclusive amount; optional deduction for bank transfer fees
• Registration number check — format check for T + 13 digits, plus the corporate-number check digit for corporations
• New invoice command — client name suggestions from past invoices, automatic sequential numbering (2026-09-001), due date from payment terms such as 月末締め翌月末払い
• Amount helpers — format a selected number as ¥1,234,567, 123万4567円, or 大字 (金壱拾弐万参千四百五拾六円也) for receipts
• Print-ready — issuer details, registration number and bank account come from settings; Export to PDF produces a clean invoice
• Works offline; no external services, no telemetry

Usage

1. Open Settings → Japanese Invoice Helper and fill in the issuer section (name, address, registration number, bank account).
2. Run the command Create new invoice. A note like the one below is created in your invoice folder and opened.
3. Edit the table; switch to reading view (or export to PDF) to see the invoice.

---
type: invoice
number: "2026-09-001"
client: "株式会社サンプル"
issued: 2026-09-30
due: 2026-10-31
withholding: true
status: unpaid
---

| 品目 | 数量 | 単価 | 税率 |
|---|---:|---:|---|
| 記事執筆（3本） | 3 | 30,000 | 10% |
| 取材交通費 | 1 | 5,000 | 10% |

```invoice

### Frontmatter keys

| Key (aliases) | Meaning |
| --- | --- |
| `number` (`請求番号`) | Invoice number |
| `client` (`宛先`, `取引先`) | Client name; the honorific (御中) comes from settings or `client_suffix` |
| `issued` (`発行日`), `due` (`支払期限`) | Dates (`YYYY-MM-DD`) |
| `subject` (`件名`) | Subject line |
| `withholding` (`源泉徴収`) | `true` / `false` |
| `withholding_base` | `excl` (before tax, default) or `incl` |
| `deduction` (`振込手数料`) | Amount deducted from the payable |
| `status` | `unpaid` / `paid` — shown as a badge on screen only |
| `note` (`備考`) | Remarks printed at the bottom |
| `title` | Document title (default 請求書; use 見積書 etc.) |

The same keys can be written inside the `invoice` code block as `key: value` lines, and a table inside the block takes precedence over the note's table, so a self-contained block also works.

### Table columns

Headers are matched by name: 品目/内容/item, 数量/qty, 単価/unit price, 金額/amount, 税率/rate. Rate cells accept `10%`, `8%`, `軽減`, `非課税`, or blank (default rate from settings). Negative amounts work as discounts.

## Disclaimer

This plugin performs arithmetic according to publicly documented rules; it is not tax advice. Rates and thresholds are settings so they can be adjusted when the law changes. Verify invoices with your accountant or the National Tax Agency guidance where needed.

## Development

```bash
npm install
npm run dev
npm test
npm run lint

License

MIT

---

日本語

Markdown で請求書（適格請求書）を書き、消費税・源泉徴収・支払期限を自動計算して、そのまま PDF に出力できる Obsidian プラグインです。

機能

• frontmatter にメタ情報、本文に明細テーブル、invoice コードブロックで請求書を描画
• 消費税は税率ごと（10%／8%軽減／非課税）に集計し、税率ごとに1回だけ端数処理（切り捨て・四捨五入・切り上げを選択可）
• 源泉徴収税（100万円まで10.21%、超過分20.42%）を税抜または税込ベースで計算。振込手数料などの控除にも対応
• 登録番号（T＋13桁）の形式チェック。法人の場合は法人番号のチェックデジットも検証
• 「新しい請求書を作成」コマンド：過去の宛先を候補表示、連番の自動採番、支払条件（月末締め翌月末払い など）から支払期限を計算
• 選択した数値を ¥1,234,567／123万4567円／大字（金壱拾弐万参千四百五拾六円也）に変換
• 発行者情報・登録番号・振込先は設定に一度入れれば全請求書に印字。「PDFにエクスポート」でそのまま送付可能
• 通信なし・外部サービスなし

使い方

1. 設定 → Japanese Invoice Helper で発行者情報（氏名／屋号、住所、登録番号、振込先）を入力
2. コマンド 新しい請求書を作成 を実行すると、請求書ノートが作成されて開きます
3. 明細テーブルを編集し、閲覧モードに切り替えると請求書が表示されます

免責

本プラグインは公開されているルールに基づく計算を行うものであり、税務上の助言ではありません。税率やしきい値は法改正に備えて設定で変更できます。必要に応じて税理士や国税庁の案内でご確認ください。