Compliance

Navigating Japan’s Upcoming e-Tax System Overhaul: What Expats & Businesses Must Know

Japan’s tax authority is rolling out a major digital transformation—including updated tax forms, new submission formats, and e-Tax system maintenance in September 2026. Here’s how to prepare.

By NomadicTax Research Team • 5-8 min read • September 15, 2026

## What’s Changing 🔧 Japan’s National Tax Agency has announced that on **September 24, 2026** the **国税システム (National Tax System, often called KSK2)** will go live. Key updates will include: - New formats for various **申告書** (tax return forms), **申請書** (applications), and **法定調書** (statutory reports) with updated field layouts and color schemes (most will now be black-and-white). ([nta.go.jp](https://www.nta.go.jp/taxes/shiraberu/sodan/system.htm?utm_source=openai)) - A shift from using **fixed IP addresses** for e-Tax system access to **dynamic IP addressing**—important for software vendors or institutional users who rely on IP filtering or trusted-host configurations. ([nta.go.jp](https://www.nta.go.jp/taxes/shiraberu/sodan/system.htm?utm_source=openai)) - Expansion of **electronic notification (“処分通知等”)** delivery options: the default consent method for e-notifications will change from case-by-case to **advance single consent (事前の一括同意)**. ([nta.go.jp](https://www.nta.go.jp/taxes/shiraberu/sodan/system.htm?utm_source=openai)) - Display of **submission date (提出年月日)** directly on form headers in services that allow document retrieval. ([nta.go.jp](https://www.nta.go.jp/taxes/shiraberu/sodan/system.htm?utm_source=openai)) ## How This Affects Expats & Businesses ### For Expats: - If you **left Japan and returned** (or vice versa), ensure your tax obligations are up to date, as **年末調整 (year-end adjustment)** and **確定申告 (tax return)** rules will apply differently depending on your residency status. Forms may look different after September 24. ([nta.go.jp](https://www.nta.go.jp/taxes/shiraberu/taxanswer/gensen/2518.htm?utm_source=openai)) - **扶養控除 (Dependent deductions)** and related documents involving overseas family members may require updated or additional paperwork (translations, proof of relationship, etc.). These are already in effect for some categories since December 1. ([nta.go.jp](https://www.nta.go.jp/taxes/tetsuzuki/shinsei/annai/gensen/kokugai/?utm_source=openai)) ### For Businesses / Software Providers: - If you provide payroll or financial reporting services, your systems may need updating: new **法定資料** (statutory materials) submitted via optical disk or magnetic media will require compliance with updated data standards. Documents such as 源泉徴収票 (withholding slips) will see format changes. ([nta.go.jp](https://www.nta.go.jp/law/tsutatsu/kobetsu/hotei/kaisei/260630/index.htm?utm_source=openai)) - The schedule for e-Tax specification documents (“仕様書”) is publicly posted, with the final version taking effect alongside the KSK2 roll-out. Ensure that your software is compliant by the key dates listed. ([e-tax.nta.go.jp](https://www.e-tax.nta.go.jp/shiyo/keikaku.htm?utm_source=openai)) ## Practical Tips to Be Ready 1. **Check your current software/vendor compatibility**: If your payroll or filings software uses old formats, forms or conventions, schedule updates well before September. 2. **Switch to e-Tax / My Number login methods**: Since login flows and identifiers may change, adopting the マイナンバーカード方式 where possible can avoid issues. Note that the older ID & Password方式 will be discontinued starting from **令和9年分 (tax year 2027)**. ([e-tax.nta.go.jp](https://www.e-tax.nta.go.jp/toiawase/qa/kanbenka/01.htm?utm_source=openai)) 3. **Review submission deadlines**, especially for statutory reports like 源泉所得税支払報告書, 源泉徴収票, etc. After September 24, you must use the new formats. ([nta.go.jp](https://www.nta.go.jp/users/gensen/2026kiso/pdf/0026005-024.pdf?utm_source=openai)) 4. **Maintain records of electronic‐notification consent**: If you prefer to receive tax authority notices electronically, you’ll likely be required to provide advance blanket consent rather than per notification. ([nta.go.jp](https://www.nta.go.jp/taxes/shiraberu/sodan/system.htm?utm_source=openai)) 5. **Monitor maintenance windows**: e-Tax will be unavailable during specific time periods around system migration. Plan submissions accordingly. ([e-tax.nta.go.jp](https://www.e-tax.nta.go.jp/topics/2026/topics_20260422.htm?utm_source=openai)) ## Example Scenario > **Maria**, a U.S. citizen working in Tokyo as a contractor, receives income from abroad and has a dependent living overseas. Under the new system: > > - She must check whether her dependent qualifies for dependent deduction, and gather necessary documentation (translated, proof of relationship). ([nta.go.jp](https://www.nta.go.jp/taxes/tetsuzuki/shinsei/annai/gensen/kokugai/?utm_source=openai)) > - When submitting her year-end tax return after September 24, her withholding slips (源泉徴収票) will be in the new format, so she must ensure her employer or payroll service is compliant. ([nta.go.jp](https://www.nta.go.jp/users/gensen/2026kiso/pdf/0026005-024.pdf?utm_source=openai)) > - She decides to use My Number login to avoid issues with deprecated ID & Password login. ([e-tax.nta.go.jp](https://www.e-tax.nta.go.jp/toiawase/qa/kanbenka/01.htm?utm_source=openai)) ## Bottom Line The KSK2 system overhaul starting **September 24, 2026** is a major milestone in Japan’s tax digitalization. Whether you’re an expat submitting your first Japanese tax return or a business managing payroll and filings, it’s essential to stay ahead: ensure updated forms, compliant systems, and timely submissions to avoid filing issues or penalties.