The answer depends on what the document is and what you need the client to do with it. A proposal the client needs to review and approve has different requirements than a contract they need to sign, which has different requirements than a deliverable they're archiving. Getting this right means fewer back-and-forth emails about file issues and a more professional impression.
For Proposals and Reports: Readable, Compressed, Protected
Client-facing documents meant for reading โ proposals, reports, presentations, case studies โ should open quickly, look exactly as designed, and not be unnecessarily large. The priorities are: all fonts embedded so the layout renders correctly, file size compressed enough to open and email easily, and optionally, edit restrictions set so the client can't accidentally modify the content.
For these documents, a standard PDF with embedded fonts, compressed with PDF Compression to under 5MB, is the right format. Don't password-protect these unless there's a specific reason โ making a client enter a password to open a proposal creates friction before they've even read the first line.
For Contracts and Agreements: Clean, Signable, Locked After Signing
Contracts need to be clear documents with no ambiguity about what version was agreed to. Send the contract as a standard PDF โ no password required to open, but ideally with edit restrictions so the client can't alter the terms. Make sure the document has genuine, selectable text (not a scan) so the client can read it easily and so it remains usable long-term.
Once signed by both parties, the fully executed version should be sent with edit restrictions applied โ or simply noted in the email that this is the final signed version. Some businesses apply a password to the signed version to prevent any further modifications; others rely on convention and the email timestamp as the record.
For Invoices: Simple, Consistent, Easy to File
Invoices get filed by the client's accounts payable team and need to be easily searchable. A small, clearly named PDF with selectable text makes their filing easier โ and reduces the chance of a payment delay because someone couldn't find or process your invoice. Keep invoices under 500KB, use a consistent naming format, and make sure the text is real (not a scan or image).
Some clients' accounting systems require specific PDF settings โ no password protection, no restrictions on printing, text must be selectable. If a client ever mentions invoice processing issues, these are the first things to check.
For Deliverables and Final Work Product: Archival Quality
Work product delivered to a client โ final reports, design files exported as PDF, completed documentation โ should be in the highest quality format appropriate to the content. For documents the client will keep long-term or share internally, PDF/A is worth considering: it's self-contained, guaranteed to remain readable without external dependencies, and accepted by most archiving systems.
For design-heavy deliverables where visual quality matters, don't compress aggressively. The client is paying for the work product โ deliver it at full quality and let them compress if they need a smaller version for a specific purpose.
Universal Best Practices Regardless of Document Type
- Embed all fonts so the document renders correctly regardless of what fonts the client has installed
- Use real text, not scanned images โ the client should be able to search and select text in any document you send
- Name files professionally: ClientName_DocumentType_Date.pdf
- Keep file size under 10MB for emailed documents; use a file sharing link for anything larger
- Test-open the file before sending โ verify it looks right and nothing is missing
A PDF that opens cleanly, looks exactly as intended, and is easy to file is a small but consistent signal of professional quality. It's the kind of thing clients don't notice when it's right but definitely notice when it's wrong.