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How to fax the IRS online: use the number in your notice

Learn how to fax the IRS online using the fax number in your notice, protect tax documents, keep confirmation and choose one-time vs subscription fax.

By FaxScout Editorial TeamLast verified September 16, 2026Research methodology
Affiliate disclosure: FaxScout may earn a commission from qualifying purchases. Commissions do not buy rankings. How we make money.

Some IRS notices explicitly allow a response by online fax, but there is no single universal IRS fax number that FaxScout should publish as a shortcut. Use the fax number and instructions in your specific IRS notice or form, confirm the destination before sending, and keep the transmission confirmation with your records.

Research status Desk researchFact check September 16, 2026Primary providers sourced 5See testing status →

FaxScout verdict

Current desk-research leader

Fax.Plus

Best balanced choice for many small-business and team workflows.

9.1/10
Fax.Plus
Best balanced choice for many small-business and team workflows
Desk research9.1/10

From $6.99/mo; Business $27.99/mo; Enterprise $79.99/mo

  • Clear 200 / 500 / 1,000+ page ladder
  • Email-to-fax and mobile apps
  • Business team/admin controls
  • Enterprise API, SSO, BAA and data residency
Visit Fax.PlusVerify pricingRead full review

Avoid if: Not the economical HIPAA choice for a small practice because Fax.Plus lists BAA/HIPAA on Enterprise only.

What matters for this decision

01Use the exact number from the IRS notice
02Protect sensitive tax documents
03Keep a delivery confirmation
04Choose one-time vs recurring fax based on actual need

Side-by-side shortlist

ProviderStarting priceAllowanceHIPAA / BAANumberPortingEmail faxAPIScore
Fax.PlusBest balanced choice for many small-business and team workflowsFrom $6.99/mo; Business $27.99/mo; Enterprise $79.99/mo200 (combined)Enterprise only / YesYesPremium+Yes; HIPAA accounts use the dedicated TLS-enforced @tls.fax.plus routeEnterprise9.1/10
Dropbox FaxGood for occasional sending and Dropbox-adjacent workflows5 one-time free outbound pages; pay-as-you-go $0.99 for first 10 pages, then $0.20/page5 (paygo)Not verified for standard fax plans / Not verifiedPaid plansProfessional / Small Business; US/CanadaPaid plansAPI plan8.0/10
FaxZeroOccasional one-off outbound faxing without a subscriptionFree: up to 3 pages + cover, max 5/day; paid $3.29/fax up to 25 pages3 (oneoff)No / NoNoNoNoNo7.6/10

Published plan facts use the provider verification dates maintained in FaxScout’s research data. “Verify” means the provider does not expose a sufficiently clear public answer for FaxScout to state it as fact.

Practical workflow

  1. Choose a compatible service.Confirm the exact workflow and plan before uploading sensitive documents.
  2. Prepare the document.PDF is the safest common format for predictable rendering.
  3. Verify the destination number.Avoid preventable misroutes before transmission.
  4. Send and retain status.Keep the delivery record when the document matters.

Do not use a generic “IRS fax number”

Use your notice. IRS fax destinations vary by notice, processing location and purpose. Read the notice carefully and use the exact number printed there or in the applicable IRS instructions.

Before sending tax documents online

Confirm the fax number against the current IRS notice or form instructions.Send only the documents requested and include any required response form or notice stub.Review the online fax provider’s privacy and security policies before uploading sensitive tax records.Keep the sent-document copy and delivery confirmation with your records.Do not send a duplicate by mail unless the IRS instructions tell you to do so.

One-time fax or subscription for IRS documents?

For a single response, compare the one-time fax guide. For a tax or accounting office that sends documents throughout the year, compare a recurring business service and model peak-season volume.

How FaxScout would make the decision

Start with non-negotiables: BAA eligibility, monthly volume, existing-number continuity, team size and API/integration requirements. Then compare total expected cost. Cosmetic features are tiebreakers, not reasons to ignore a major constraint.

FS

FaxScout Editorial TeamResearch + fact checking

We use primary provider documentation for plan facts and label every untested performance dimension. See who creates FaxScout research →

Frequently asked questions

Can I fax the IRS with an online fax service?

Yes for IRS processes that list fax as an accepted response method. Current IRS notice pages such as CP75 explicitly say taxpayers may use a standard fax machine or online fax service.

What fax number should I use for the IRS?

Use the fax number in the specific notice, form instructions or IRS page for your case. Do not rely on a generic fax number copied from an unrelated notice.

Should I mail the same documents after faxing them?

Follow the instructions for your specific notice. Some IRS pages explicitly tell taxpayers not to mail a duplicate response after faxing.

Sources & verification

Material plan facts were checked against primary documentation at the verification date shown above.

Best one-time online fax services: pay per fax without a subscription Best online fax services for accountants and CPA firms Fax.Plus review: pricing, plans, apps and who should use it Online fax cost calculator: estimate monthly plan cost

Continue your research

How to fax from Gmail without a fax machine How to fax from Outlook and Microsoft 365 How to fax from an iPhone without a fax machine How to fax the IRS online: use the number in your notice How to fax from a Mac without a fax machine How to receive a fax without a fax machine