When the Hometax e-Tax Invoice Secure Mail (NTS_eTaxInvoice.html) Won't Open

When an electronic tax invoice is issued, Korea's Hometax sends a notification email with an HTML attachment such as NTS_eTaxInvoice.html. Open it and you often get a blank page, no password prompt, or a wall of unreadable characters as if in Notepad. The file isn't broken — this is what it is supposed to look like.

Why nothing shows up

The attachment is a 'secure mail'. The invoice content sits encrypted inside the file; when opened, the page fetches a script from the tax office server (srtk.hometax.go.kr), asks for a password, and decrypts the content inside the browser. So in these situations nothing appears:

• •Opened in a mail client's attachment preview (Outlook, webmail, phone mail apps) — previews don't run scripts.
• •Scripts blocked by a work PC's security policy or browser settings.
• •No internet connection — the decryption script has to be fetched from the tax office server.
• •Opened in a text editor — the content is encrypted, so garbled-looking text is normal.

How to open it in the browser

1. 1Save the HTML attachment to your PC or phone (Download in the mail app).
2. 2Open the FileKeeps File Viewer and select or drag in the file.
3. 3The tax office's password prompt appears in the Preview tab. Enter the password described in the email (usually the 10-digit business registration number; for individuals a rule such as the first digits of the resident number, as stated in the email) and confirm.
4. 4The invoice appears in place. Use the page's own Print button to print or save as PDF, and its save button for any attachments.

How it works — and the limits

The viewer loads the HTML in a frame with an origin separate from the site and allows scripts to run, so the tax office script can show its password prompt and decrypt the content as designed. Because that script comes from the tax office server, you need an internet connection, and it won't open while their server is under maintenance. Without the password it naturally can't be decrypted — in that case, log in to Hometax and check the same invoice under 'e-Tax Invoice inquiry'.

Do other secure mails work too?

Secure mails from card companies, banks, and carriers (statement HTML attachments) are built similarly and mostly open the same way. Each company's password rule (birth date, last card digits, and so on) is stated in the email. Scripts differ by company, so some may not open — check on that company's website in that case.