You're about to send something that carries real consequences—W-2s, 1099s, K-1s, bank statements, ID scans, payroll reports. You want your CPA (or client) to get it fast, but you do not want those files living forever in random inboxes or shared drives. You're right to pause. The IRS and FTC both expect professional-grade safeguards for taxpayer data, and a surprising number of incidents come from plain old email mishaps and mis-sharing—not "hackers in hoodies."

According to Verizon's Data Breach Investigations Report, 61% of data breaches involve email-based document leaks. Meanwhile, secure document sharing platforms reduce breach risk by 85%.

Below is a clear, reality-tested playbook. It keeps the workflow humane while giving you real control.

1) Why you need this (beyond "being careful")

Tax files contain the keys to a person's financial identity. Once an attachment is sent, it's trivially forwarded, archived, or synced to devices you'll never see. Regulators explicitly push firms to encrypt transmissions and control access; the IRS even requires password-protected or encrypted documents when you email them directly.

The FTC Safeguards Rule mandates that financial institutions implement comprehensive security programs, including encryption for sensitive customer information—which includes taxpayer data.

If you're a founder or finance lead, this is not about paranoia. It's table stakes: protect people, meet expectations, and avoid the reputation hit that comes from a sloppy leak.

2) What "secure enough" must actually do in 2025

Think in bundles, not features:

Gatekeeping: Only named people (or trusted domains) can open. No "anyone with the link" for sensitive files. See our guide on access control best practices.
Confidentiality in transit & at rest: Use modern encryption. (Native tools like Microsoft 365 provide message encryption; PDFs can be encrypted with AES-256.)
No raw attachments by default: Email should carry the notification, not the payload. Learn more in our secure email sending guide.
Revocation & expiry: You can turn access off or let it expire. This is essential for document lifecycle management.
Attribution & logging: You can reasonably tell who viewed what, when. Check out page-level analytics for complete visibility.
Deterrence: Watermarking and "do not forward" style controls reduce casual leaks. (Note: Gmail Confidential adds sharing friction but isn't end-to-end encrypted—don't overtrust it.)
Usable for normal people: If the flow is painful, recipients route around it.

That's the bar we'll hit below.

3) How to send tax documents securely with Peony (step-by-step)

Peony provides enterprise-grade secure document sharing with AES-256 encryption, dynamic watermarks, granular access controls, and complete audit trails.

Peony's model is simple: email (or text) is the doorbell, Peony is the vault.

Step 1 — Collect & stage

Upload your tax files (PDFs, spreadsheets, ID images) into a Peony "room"—for example, "2024 Taxes – Client Uploads" or "CPA – Q1 Compliance Docs". Keep each relationship in its own space so access is clean.

This mirrors the approach in our confidential documents guide for organized, controlled sharing.

Step 2 — Define who gets in

Grant access to specific email addresses (your CPA's team) or approved domains (their firm). This identity-bound gate replaces risky one-size passwords. See password protection options for additional layers.

Step 3 — Set protective defaults

View-only for external recipients.
Downloads off unless there's a clear business reason.
Optional expiry so access naturally ends after filing.

Step 4 — Add dynamic watermarking & screenshot deterrence

Peony can display per-viewer watermarks (name/email/timestamp) across pages and discourage trivial screen capture. If something leaks, it's attributable—strong behavioral deterrence.

Our watermarking guide explains how this protects against unauthorized sharing, similar to the protection outlined in PDF forwarding prevention.

Step 5 — Share a single secure link

Send one Peony link in your email: "Here's the secure link to this year's tax packet." The link always points to the current set; no risky attachments, no version chaos.

This approach is detailed in our secure file sharing best practices.

Step 6 — Update, monitor, revoke

Replace or add documents without changing the link.
See who accessed what and when (lightweight analytics).
Revoke an individual, a domain, or the entire room after filing.

This satisfies the "bundle" above with minimal friction—exactly what IRS guidance and FTC expectations require: encryption, access control, and process discipline.

4) Other methods if you can't use Peony (4 solid options)

Method A — Encrypted email in Microsoft 365 ("Encrypt" / "Do Not Forward")

In Outlook, choose Options → Encrypt or Do Not Forward to send protected messages (recipients can be restricted from forwarding/printing, and content is encrypted). Good for Microsoft-centric orgs and some external recipients. Caveat: Compatibility and UX can vary for non-M365 users.

Microsoft's documentation covers the full implementation.

Method B — Properly password-protected PDFs (AES-256)

Use Adobe Acrobat: All tools → Protect a PDF → Encrypt with Password. Share the password out-of-band (phone/SMS). Strong at-rest protection; weak on control (recipients can still share file + password, and you can't revoke).

See our password protect PDF guide for detailed steps. Also check our Excel file protection guide for spreadsheet-specific security.

Method C — Encrypted archives (ZIP/7z with AES-256)

Bundle documents into an encrypted archive and send the password separately. This is a common CPA workflow. Same caveats as password-PDFs: once opened, you lose visibility.

Our confidential documents guide covers secure password handling practices.

Method D — Client portals / secure firm upload links

Many CPA firms run portals or IRS Secure Messaging for specific use cases. Use these if they're offered; they centralize access and logging. Check scope/limits—IRS Secure Messaging only accepts certain forms and isn't a universal inbox replacement.

Two caution flags: • Gmail Confidential adds sharing friction but isn't true end-to-end encryption; treat it as light protection, not a vault. • NIST password guidance favors long, unique passphrases over quirky complexity—use length and uniqueness for any secrets you set.

5) Practical setup tips (the tiny habits that prevent big problems)

Adopt one rule: If we'd be uncomfortable seeing these tax files forwarded, we don't send them as attachments. We use a secure link. Full stop. (The IRS itself requires encryption/passwording when you email them—so mirror that standard with everyone.)
Standardize your email copy: "Sharing via a secure link so you always see the latest version and we keep your data properly protected on our side." This reads as professional, not paranoid.
Kill "anyone with the link" for tax folders in your cloud drives. Use "specific people" and expiry everywhere sensitive data lives. Our secure file sharing guide covers proper access controls.
Share secrets out-of-band. If you must use passwords (PDF/ZIP), send the password by phone or SMS—not in the same email thread. This is covered in email security best practices.
Review access after filing. Once returns are accepted and books are closed, revoke external access and archive the space. Quiet hygiene > frantic cleanup.
Stay aligned with guidance. IRS Pub. 4557 lays out baseline safeguards and points to FTC Safeguards Rule obligations for firms handling taxpayer data. If you're a tax pro or finance shop, keep your Written Information Security Plan current.

Bottom line

"Secure" tax document sharing isn't one magic feature; it's a calm, repeatable flow: identity-bound access, encrypted delivery, no raw attachments by default, revocation on demand, and clear attribution. Peony gives you that flow out of the box. When you can't use it, pick one of the four methods above and apply the same principles.

Secure Your Documents

How to Send Tax Documents Securely in 2025: IRS-Compliant Guide to Protecting W-2s, 1099s & Financial Records