For most of a firm's paperwork, engagement letters, organizers and consent forms, any reputable e-signature tool will do. Form 8879 (and 8878 for extensions) is the exception. The IRS allows electronic signatures on these authorizations, but Publication 1345 attaches conditions to the software and to the preparer, and a signature collected with nothing more than an email link misses them. This page reads those conditions from the December 2025 revision of Publication 1345 and matches them against what each vendor documents. We have not tested the products.
For whom: a tax preparer, enrolled agent or small CPA firm that collects 8879s from clients who are not in the office. Not for: firms whose tax software already includes Form 8879 e-signature with identity verification; see the counter-case below.
What Publication 1345 requires
| Requirement | What the publication says |
|---|---|
| Method | No specific technology; a typed name, a stylus mark, a shared secret or a digital signature are all acceptable methods |
| Identity verification standard | In accordance with NIST SP 800-63 at level 2 with knowledge-based authentication, or a higher assurance level |
| Remote signer | The preparer records name, Social Security number, address and date of birth, and verifies them through record checks (credit bureaus or similar databases) |
| In-person signer | Inspect a government photo ID, unless there is a multi-year relationship with a prior verified return |
| Failed verification | After three failed knowledge-based authentication attempts, obtain a handwritten signature |
| Data the software must record | Image of the signed form; date and time; the taxpayer's IP address and login (remote); the identity-verification result; the signing method or an audit trail |
| The record | Signature linked to the form so it cannot be copied to another record; tamper-proof after signing; retrievable and printable |
| Joint returns | Each taxpayer identified and authenticated separately |
The IRS's separate list of paper forms that accept e-signatures, now an archived page, does not change this: Forms 8879 and 8878 follow Publication 1345.
Which tools document knowledge-based authentication
| Tool | What its own documentation says | Price of the check |
|---|---|---|
| BoldSign | Knowledge-based authentication with questions generated from public records, for U.S. recipients only; the sender sets the number of attempts before the document locks | Published: $1.50 per attempt as an add-on on Business and higher plans; ID verification $2 per verification |
| Docusign | Knowledge-based questions from public databases, available only to US-based customers, alongside ID verification and phone authentication | Not published on the product page |
| OneSpan Sign | Knowledge-based authentication through LexisNexis, with questions from the signer's credit report; enabled by contacting support | Not published |
None of these vendors' pages says that its configuration satisfies Publication 1345, and we do not say so either. What the documentation does show is that each tool can put a knowledge-based check in front of the signature. Matching the rest of the list (three-attempt rule, recorded fields, separate spouses) is a configuration you set and verify.
Our pick
BoldSign for a small practice. It is the only one of the three whose pricing page states the cost of a knowledge-based check, so a firm can budget its filing season before signing a contract, and its sender-set attempt limit can be matched to the three-attempt rule. Confirm on a test envelope that the completed audit trail shows the verification result, the IP address and the time, because those are the fields the IRS can ask for.
- Pick Docusign instead if the firm already runs engagement letters and other agreements on it and wants the 8879 check in the same platform; ask for the price of the authentication method before the season.
- Pick OneSpan Sign instead for a larger firm buying under an enterprise contract, where a support-enabled KBA and a negotiated price are normal.
Counter-case: if your tax preparation software offers Form 8879 e-signature with knowledge-based authentication built in, use it. Publication 1345 places the requirements on the software and the preparer together, and the tax software already holds the return the form authorizes. Keep a separate e-signature tool for the rest of the engagement.
A checklist for the season
- Turn on knowledge-based authentication for every remote 8879, and set the attempt limit to three.
- Send one envelope per taxpayer on a joint return, or confirm the tool authenticates each signer separately.
- Write down the fallback: after a failed check, a handwritten signature.
- Export one completed test record and confirm it contains the signed form image, date and time, IP address, login and the verification result.
- Store completed 8879s outside the vendor account in a system that keeps them unaltered and printable.
For when a typed name is enough outside the IRS context, see typed names and /s/ signatures; for other agency rules, see IRS, USCIS and notarized documents.
Traceable evidence
Sources for this decision
- regulatorPublication 1345 (Rev. 12-2025), Handbook for Authorized IRS e-file Providers of Individual Income Tax ReturnsInternal Revenue Service · checked Oct 27, 2026 · supports: IRS Publication 1345 (Rev. 12-2025) guidance that taxpayers may e-sign Forms 8878 and 8879 when the software meets IRS requirements: acceptable methods include a typed name, a stylus mark and a shared secret; the software must record the signed form image, date and time, IP address and login for remote signing, identity-verification results and the signing method; identity verification must meet NIST SP 800-63 level 2 with knowledge-based authentication or higher; remote signers are verified through record checks; three failed KBA attempts require a handwritten signature; signed records must be tamper-proof. It does not certify any e-signature product.Open source ↗
- regulatorDetails on using e-signatures for certain formsInternal Revenue Service · checked Oct 27, 2026 · supports: IRS list of paper-only forms that may carry electronic signatures, the accepted signature methods and the statement that the policy was extended indefinitely and integrated into IRM 10.10.1; the page is marked archival, and it does not cover forms outside the list or e-file signature rules.Open source ↗
- vendorBoldSign official product siteBoldSign · checked Aug 5, 2026 · supports: Vendor-published product scope used to verify capabilities relevant to this buyer context: Product and operations teams comparing web signing with API and embedded workflows. It does not prove the guide's fit verdict, configured performance, current pricing or compliance.Open source ↗
- vendorDocusign official product siteDocusign · checked Aug 5, 2026 · supports: Vendor-published product scope used to verify capabilities relevant to this buyer context: Organizations evaluating a broad agreement workflow and integration ecosystem. It does not prove the guide's fit verdict, configured performance, current pricing or compliance.Open source ↗
- vendorOneSpan Sign official product siteOneSpan Sign · checked Aug 5, 2026 · supports: Vendor-published product scope used to verify capabilities relevant to this buyer context: Regulated and enterprise buyers evaluating authentication, evidence, and controlled workflows. It does not prove the guide's fit verdict, configured performance, current pricing or compliance.Open source ↗
- vendorBoldSign pricing page, plan features and add-onsBoldSign · checked Oct 27, 2026 · supports: BoldSign's pricing page as read on October 27, 2026: the free Essential plan with 25 envelopes a month (five until business details are verified for personal email signups), one user and two templates with an audit trail, the paid plan tiers, and identity verification at two US dollars per verification and knowledge-based authentication at one US dollar fifty per attempt listed as add-ons for Business, Premium and Enterprise API; it does not label which displayed price set is yearly or prove any legal outcome.Open source ↗
- vendorKnowledge-based authentication in BoldSignBoldSign · checked Oct 27, 2026 · supports: BoldSign help article stating that knowledge-based authentication asks signers for legal identity details and questions generated from public records before they open and sign, that it is available only for U.S.-based recipients and that senders set the number of attempts before the document locks; it does not name the data provider, the plan or the price.Open source ↗
- vendorDocusign Identify, signer identity verificationDocusign · checked Oct 27, 2026 · supports: Docusign's Identify product page describing knowledge-based authentication from public-database questions, available only to US-based customers, automated ID verification and phone authentication by one-time passcode; it lists no price and does not prove that a configuration meets IRS Publication 1345.Open source ↗
- vendorOneSpan Sign documentation, authenticating signersOneSpan · checked Oct 27, 2026 · supports: OneSpan Sign documentation stating that knowledge-based authentication relies on the third-party provider LexisNexis, verifies the signer with questions about the signer's personal credit report and must be enabled by contacting OneSpan support; it does not state the price, plan or any IRS acceptance.Open source ↗