SealDoc Blog
In-depth articles on PDF/A-3, e-invoicing, audit trails and compliance.
Emailing an invoice with a work order and photos: what goes in the email and what goes in the invoice
Sending a work order, photos or a quote with your invoice: why those documents belong next to the invoice and not inside it, what EN 16931 says about them, and how you send invoice and attachments in one email from SealDoc.
Read moreInvoicing over Peppol in SealDoc: live within two weeks
Within two weeks you send your invoices from SealDoc directly over the Peppol network, in every paid package. What Peppol is, who it matters for, and how it works in SealDoc.
Read moreThe SealDoc app is coming: invoice and scan from your phone
SealDoc is coming to iPhone and Android. Create an invoice wherever you are, scan the work order with your camera and email both to your customer in one go. Here is what the app does.
Read moreEN 16931 code lists: every code an e-invoice needs
The complete reference to the EN 16931 code lists: VAT categories, exemption reasons, payment means, units, document types, countries and electronic addresses. Per list the field, the BR-CL rule and the codes you actually use.
Read moreKeeping invoices in the Netherlands: 7 years, and how a digital invoice stays provably genuine
How long do you keep invoices in the Netherlands, in which form, and how do you show seven years later that a digital invoice is genuine and unchanged? The rules of the Dutch tax authority, and how SealDoc makes every invoice provable.
Read moreXRechnung validation errors: every BR-DE rule explained, with the fix
BR-DE-15, BR-DE-2, BR-DE-1 and every other rule of XRechnung 3.0: what each one checks, why an invoice fails on it and how to fix it. With a free validator that runs both EN 16931 and BR-DE.
Read morePeppol in Germany: what a valid BIS 3.0 invoice additionally requires
When seller and buyer are both in Germany, a Peppol BIS 3.0 invoice must also pass 31 German rules (DE-R). What they require and how SealDoc checks them.
Read moreHow to Create an XRechnung: Required Fields (2026)
How to create an XRechnung: every BR-DE mandatory field, the Leitweg-ID, when foreign sellers need one, and the German deadlines up to 2028.
Read moreYour client invoices France: the four questions to ask this month
France switched on its e-invoicing receiving obligation on 1 September 2026. For accountants with clients who export to France, this is a short checklist of which clients are affected, what to ask them, and what to do when the answer is no.
Read moreDefensible deletion: how to destroy personal data and keep the proof
Deleting personal data is easy. Proving you deleted the right data, at the right time, for the right reason is the hard part. This article explains defensible deletion, why delete-and-forget fails an audit, and what a certificate of destruction should actually contain.
Read moreGDPR right to erasure for HR records: how to delete employee data and prove it
An employee asks you to delete their data. Your payroll retention obligation says keep it for seven years. This article explains how the GDPR right to erasure applies to HR records, when you must refuse it, and how to prove that you deleted what you were allowed to delete.
Read moreHow long can HR keep employee and candidate data? EU retention periods
Rejected candidates: about 4 weeks without consent, up to 12 months with it. Payroll: 5 to 10 years. Every HR record type, and the law behind each period.
Read moreThe best RFC 3161 timestamp services for EU compliance (2026)
An honest comparison of RFC 3161 timestamp providers for EU compliance: qualified eIDAS trust service providers, global CAs, free options, and evidence platforms. Which one you need depends on whether you want a timestamp token or a complete, verifiable evidence artifact.
Read moreLegal document retention periods in the EU: which document, how long, which law
A practical reference for EU document retention periods by document type and jurisdiction, covering invoices, contracts, employment and accounting records across Germany, France, the Netherlands, Belgium, and Poland. Updated for Germany's 2025 reduction of the invoice retention period from ten to eight years.
Read moreRevisionssichere Archivierung under GoBD: requirements, retention periods, and the technology (2026)
Revisionssichere Archivierung is Germany's standard for storing tax-relevant documents so they stay unchangeable, complete and traceable. Here is what the GoBD requires, the retention periods that changed in 2025, and where technology like WORM storage and RFC 3161 timestamps fits.
Read moreWhy your ERP generates invoices, not evidence
ERP and accounting software are built to process transactions. That is a different job from producing verifiable evidence that a document existed in a specific form at a specific time. Here is where the gap is, and what it costs when it surfaces.
Read moreHash chains and tamper detection: how one changed byte invalidates an entire archive
A cryptographic hash chain turns a sequence of document events into a tamper-evident record. Changing any entry, even a single byte, produces a mismatch that propagates forward through every subsequent event. Here is how the construction works and what it guarantees.
Read moreAutomatic EU-compliant invoices from Dynamics 365 Business Central with SealDoc
The SealDoc Business Central connector generates Factur-X, XRechnung and Peppol BIS 3.0 invoices automatically via native BC webhooks. OAuth2, no polling, EN 16931-validated e-invoices.
Read moreAutomatic EU-compliant invoices from Odoo with SealDoc
The SealDoc Odoo connector automatically generates Factur-X, XRechnung and Peppol BIS 3.0 invoices from posted sales invoices. No manual work, EN 16931-validated e-invoices.
Read moreAutomate EU e-invoicing with the SealDoc Make connector
The SealDoc app for Make brings Factur-X invoice generation, PDF/A-3 conversion and invoice validation into your Make scenarios. No hand-built HTTP modules, no code.
Read moreAutomatic EU-compliant invoices for every WooCommerce order
SealDoc Compliance Invoices for WooCommerce auto-generates ZUGFeRD / Factur-X and XRechnung invoices the moment an order is paid. No manual work, EN 16931-validated e-invoices.
Read moreEU data sovereignty for compliance documents: why jurisdiction matters when you cannot delete the file
When a document carries a 7-year retention requirement and cannot be deleted before expiry, where it is stored becomes a legal question, not just a procurement one. Here is the case for keeping compliance-sensitive data under EU jurisdiction.
Read moreE-invoicing in Belgium from 2026: what every business needs to know
Belgium mandates structured B2B e-invoicing from 1 January 2026, with Peppol as the default. What it means for your business, suppliers and invoicing software.
Read moreFrom data to sealed PDF in one API call
Render Markdown or a JSON invoice straight into a Factur-X PDF/A-3 in a single API call. No intermediate step, no third-party tool, evidence pack included.
Read morePDF/UA-1 accessibility via API
The European Accessibility Act has applied since 28 June 2025 to services such as consumer banking and e-commerce. SealDoc adds PDF/UA-1 with one flag.
Read moreCommon Peppol BIS 3.0 validation errors and how to fix them
Peppol BIS 3.0 Schematron validation produces error messages that reference BR codes, BT numbers, and XPath locations. This article maps the most common validation failures to their root causes and fixes, covering arithmetic rules, mandatory field errors, and country-specific extension failures.
Read moreHow to generate a compliant e-invoice with n8n and SealDoc
Step-by-step guide to generating Factur-X e-invoices in n8n with the SealDoc node. Structured fields in, a validated PDF/A-3 with embedded XML out. No code required.
Read moreFactur-X vs ZUGFeRD vs UBL, a practical guide for European invoicing
Three names, two formats, one specification underneath. Here is how Factur-X, ZUGFeRD, and UBL actually relate, when to use which, and why most cross-border pipelines need to handle all three.
Read moreFrance's e-invoicing mandate, what changes on 1 September 2026
On 1 September 2026, every business established in France has to be able to receive structured electronic invoices. The send obligation phases in through 2027. Here is what the calendar actually looks like, what to do now, and where cross-border senders fit in.
Read morePoland KSeF from 1 April 2026, what cross-border senders need to know
Poland's KSeF became mandatory on 1 February 2026 for the largest taxpayers and on 1 April 2026 for all others. What foreign suppliers need to know.
Read moreThree n8n nodes, one compliance-ready archive
How to wire SealDoc into an n8n workflow that turns every incoming PDF into a PDF/A-3 archive copy with an RFC 3161 timestamp and a hash-chained audit trail. Three connected nodes, with a configuration you can copy.
Read morePDF/A-3 vs PDF/A-1: which format do hybrid e-invoices need?
EU law does not require PDF/A: an e-invoice is structured data. Hybrid formats such as Factur-X need PDF/A-3, and here is why PDF/A-1 cannot do the job.
Read moreRFC 3161 timestamps: what they are, why they matter, and when they are legally required
An RFC 3161 timestamp proves a document existed at a specific point in time and has not been altered since. Here is why that matters for EU e-invoicing compliance and legal archival.
Read moreXRechnung 3.0: what changed and how to comply
XRechnung 3.0 introduced new mandatory fields and tightened validation. Here is what changed, who is affected, and how to generate compliant invoices.
Read moreDocument pipelines: from DOCX to PDF/A-3 to verifiable archive in one API call
Converting a DOCX to a compliant PDF/A-3 archive is a multi-step process where each step can fail silently. This article walks through what the full conversion chain looks like, what breaks at each step, and how to build a pipeline that produces verifiable archival output reliably.
Read moreHallucination-safe document workflows: using AI in legally sensitive contexts
AI systems produce plausible-looking output that may be factually wrong without signalling that anything is wrong. In legally sensitive document workflows, this requires specific architectural choices. This article describes patterns that make AI-assisted document generation safe for compliance use.
Read moreAI-generated documents and legal validity: the compliance gap
AI can generate contracts, reports, invoices, and compliance documents faster than any human. What it cannot do is guarantee that the output is legally valid. This article examines the compliance gap between AI-generated text and legally admissible documents, and what infrastructure is needed to close it.
Read moreLong-term PDF validation: why a compliant PDF today may fail verification in 2035
A PDF/A-3 file that validates correctly today may fail verification in ten years if the signing certificate has expired, the timestamp TSA certificate chain is no longer available, or the cryptographic algorithms have been deprecated. This article explains what long-term validation requires and how to build archives that remain verifiable for decades.
Read moreDigital sovereignty in document infrastructure: what it means and why it matters
Digital sovereignty for document infrastructure means controlling where your documents are stored, who can access them, and whether you can retrieve and verify them independently of any vendor. This article explains what genuine sovereignty requires and where most cloud-based document platforms fall short.
Read moreWORM storage and legal hold: when you need write-once archives
WORM storage prevents any modification to archived data at the storage layer. Legal hold suspends deletion for documents under investigation or litigation. This article explains both mechanisms, when they are legally required, and how they relate to hash-chain integrity.
Read moreTamper detection in document archives: how hash chains work
Hash chains make tampering with archived documents mathematically detectable. This article explains how SHA-256 hash chaining works, why it is tamper-evident, and how it compares to other integrity mechanisms for long-term document archives.
Read moreChain of custody for digital documents: what auditors and tax authorities actually require
Chain of custody for a digital document means being able to prove what happened to it, in what order, and by whom, from creation to archive. This article explains what tax authorities and auditors look for, and what technical mechanisms satisfy those requirements.
Read moreRFC 3161 timestamps explained, how to make a digital signature legally durable
A digital signature proves who signed a document. An RFC 3161 timestamp proves when. Here is how trusted timestamps work, why every long-term archive needs them, and how to verify one without trusting the timestamping authority more than necessary.
Read moreWhat is a Legal Evidence Pack and what goes in it?
A Legal Evidence Pack is a structured archive that proves a document existed in a specific form at a specific time and was processed correctly. This article explains what it contains, when you need one, and what the difference is between storing a document and having verifiable evidence.
Read moreXML Signature validation pitfalls in Peppol
Validating XMLDSig signatures on Peppol SMP responses is harder than it looks. Dynamic namespace prefixes, namespace promotion during re-serialization, and C14N canonicalization interact in ways that break standard .NET and Java XML signature verifiers.
Read moreHow Peppol SMP and SML discovery actually works
Peppol uses a DNS-based discovery chain to route invoices to the right Access Point. This article explains how SML and SMP discovery works, what the DNS lookup produces, and what the SMP response contains.
Read moreUBL vs CII: which invoice XML syntax should you choose?
UBL 2.1 and UN/CEFACT CII are both EN16931-compliant XML syntaxes for electronic invoices. This article explains the structural differences, which formats mandate which syntax, and the practical consequences for developers building invoice pipelines.
Read morePeppol mandate Belgium, what changed on 1 January 2026
Since 1 January 2026, businesses established in Belgium must exchange structured B2B e-invoices, Peppol by default. How to check your partners are ready.
Read moreHow to generate Peppol BIS 3.0 invoices in C#
A practical guide to generating valid Peppol BIS Billing 3.0 UBL 2.1 invoices in C#, covering mandatory fields, namespace setup, line items, tax totals, and Schematron validation with Saxon HE.
Read moreUnderstanding EN16931: Europe's invoice data model
EN16931 is the European standard that defines what an e-invoice must contain. This article explains Business Terms, Business Groups, Business Rules, and how the semantic model maps to UBL and CII, from an engineering perspective.
Read moreFactur-X vs ZUGFeRD vs XRechnung vs Peppol: what is the difference?
Factur-X, ZUGFeRD, XRechnung, and Peppol BIS 3.0 are all built on the same underlying standard but serve different markets and delivery channels. Here is a plain-language comparison.
Read moreWhat is PDF/A-3 and why it matters for e-invoicing
PDF/A-3 is the archival PDF format that lets you embed structured XML inside a long-term-readable invoice. Here is what it actually guarantees, what it does not, and why it is the default container for Factur-X and ZUGFeRD.
Read moreWhat is Peppol BIS 3.0? A practical developer introduction
Peppol BIS Billing 3.0 is the XML invoice standard used across European e-invoicing networks. A plain-language technical introduction covering UBL, EN16931, SMP discovery, and validation pitfalls.
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