> JapanHacked_
[Resolved][Severity: Minor][Unknown]

NTA: e-Tax reopens after suspicious traffic; no taxpayer-data leak

e-Tax reopened on 5 November after checks following suspicious traffic. The NTA confirmed that taxpayer information had not leaked.

Every organization listed paused its services as a precaution; none is listed as hit.

Disclosed

2026-11-04 19:00

Organizations involved

1

Leaked or at risk

Unknown

Downtime

Unknown

What happened

Emergency maintenance made e-Tax unavailable from about 11:40 on 4 November. In a 19:00 update the NTA said it had detected suspicious communications and was checking equipment. No recovery time is set. [1] [2]

What is confirmed

Jiji reports that no taxpayer-data leak has been confirmed. The notice establishes suspicious communications and a precautionary suspension, not a confirmed intrusion or leak. This is separate from the gift-tax display error disclosed in October. [1] [2]

Report dated 2026-11-05

On 5 November the NTA announced that e-Tax had reopened after required measures and safety checks. It confirmed no taxpayer-data leak; it did not establish that the suspicious traffic was a successful intrusion. [1]

Timeline

  1. Detected, Disclosed 2026-11-04
  2. Resolved 2026-11-05
  3. 1 days

Attack or cause

Method
[Unknown]
Impact
[Service outage]
Entry point
Unknown

Data exposed or at risk

–

Services hit

Organizations involved

Sources

  1. [1][Official]e-Tax再開のお知らせNTA · 2026-11-05
  2. [2][News]e―Taxに不審な通信 国税庁、一時停止にJiji Press · 2026-11-04 20:45