Document attachments in Business Central

Every record in Business Central can carry attached files — a scanned invoice on a purchase invoice, a contract on a customer, a CAD drawing on an item. BC provides several mechanisms with different storage, retention, and licensing characteristics. The decisions matter: at scale, attachments are the dominant tenant size driver.

The factbox pattern. Most BC pages display an Attachments factbox on the right. Adding a file uploads it into the Tenant Media table, linked via a Document Attachment record to the source document. The attachment stays bound to the original document; if the document is archived or posted, the attachment moves with it.

Storage in the tenant database. Files saved via the Attachments factbox land in the BC tenant database. Pros: no external service, naturally backed up with the tenant, single security model. Cons: tenant storage is metered and not cheap at scale (typically 80GB included, then per-GB charges); large attachment volumes inflate the tenant footprint and slow backups.

OneDrive integration. With Open in OneDrive and Share via OneDrive features, BC links documents stored in the user's OneDrive for Business. The file lives in OneDrive, BC stores only a link. Pros: no tenant storage cost; OneDrive licensing is already there for M365 users; collaborative editing for free. Cons: the link breaks if the file is moved or the owning user leaves; OneDrive personal scope creates governance complexity.

SharePoint integration. Often layered via custom code or AppSource extensions, SharePoint storage is the enterprise pattern. The file lives in a SharePoint document library; BC stores a link plus metadata. Pros: enterprise document management features (retention, eDiscovery, version history); centralised governance. Cons: requires SharePoint setup, library structure, permissions design.

Item attachments. Items carry a dedicated Item Attribute and Item Reference framework plus standard document attachments. Product images, spec sheets, safety data sheets — typically attached at item level. For larger image needs, item images are stored separately with a thumbnail in BC and the full image on a CDN.

Linked vs embedded. Two patterns:

• Embedded — the file binary is stored inside BC. Self-contained but storage-heavy.
• Linked — only a URL or reference is stored; the binary lives elsewhere (OneDrive, SharePoint, Azure Blob).

Most production BC tenants over a year old benefit from linked storage; embedded is fine for low-volume scenarios.

Incoming documents. A separate but related feature, Incoming Documents is a list of inbound files (vendor invoices, expense receipts) that haven't yet been processed into a purchase invoice. Workflow:

1. File arrives by email, OCR feed, or upload.
2. An Incoming Document record is created.
3. Operator reviews, optionally runs OCR (Continia, Continia Document Capture, or AppSource), and creates a purchase invoice from the document.
4. The incoming document remains attached to the resulting invoice.

This is the AP automation gateway in BC.

Retention and deletion. Attachments have no built-in retention rules — they stay until manually deleted. For SOX or GDPR-relevant data, attachments must be included in retention policies:

• Power Automate flows can periodically delete attachments older than X years.
• Manual archival to SharePoint with retention labels is the enterprise approach.
• BC's data archival tools (introduced wave-by-wave) may automate this in future.

Versioning. No native version history in BC attachments — replacing a file overwrites. SharePoint integration brings versioning. For compliance-heavy environments, this is a strong argument for SharePoint over embedded storage.

Mobile capture. BC's mobile and tablet apps support attachment capture — photograph a receipt and it attaches to the expense or purchase invoice. The image goes through OCR if configured.

Security model. Attachments inherit the host record's permissions. If a user can read the purchase invoice, they can read the attachment. For sensitive documents (contracts, salary letters), check that BC's record-level permissions match your information classification.

Common pitfalls.

• Database bloat. Years of attachments at high volume → multi-TB tenant → backup and refresh pain. Architect for external storage early.
• Broken OneDrive links. Departed users; the rebuild of links is manual. Use SharePoint or service-account OneDrive for shared business documents.
• OCR confidence ignored. OCR misreads → wrong invoice data flows through; always include a verification step before posting.
• No retention discipline. GDPR requests then become an attachment audit. Plan retention from day one.

Operational rule. For low-volume tenants (under 5 GB of attachments after a year), embedded storage is simplest. For higher volume or compliance needs, design a hybrid pattern — operational attachments embedded, archived attachments in SharePoint, links instead of binaries where possible.