Voice documents fail when they describe a personality instead of giving instructions. A usable instagram brand voice guide lets someone who joined last week write a caption that sounds like the account, without asking anyone.
Rules beat adjectives
"Friendly, bold and authentic" describes almost every brand and helps nobody. Replace adjectives with decisions: do we use contractions? Do we open with a question? Do we use exclamation marks, and how many? Do we say "we" or speak impersonally? Each is checkable, and checkable rules survive staff changes.
Pair every rule with a real example and a counter-example drawn from your own drafts. Abstract guidance gets interpreted differently by every writer; a before-and-after pair removes the ambiguity in a way no amount of description can.
What the document should contain
- Five to eight concrete rules, each with a yes and no example.
- Vocabulary you use, and vocabulary you avoid, with reasons.
- How the voice shifts by format — captions, stories, replies.
- How to handle complaints and mistakes, where tone matters most.
- Claims that are never made, regardless of phrasing.
- Who decides when a case is genuinely unclear.
The claims section is the one most often missing and the most valuable. It prevents an enthusiastic writer from promising outcomes the business cannot stand behind, which is a tone problem with real consequences.
Keeping voice consistent across people
Consistency degrades quietly as more people write. The cheapest control is a short review against the rule list — not a full edit, just a check that the rules were followed. Reviewers who edit to personal taste rather than to the document are the main reason voice guides get ignored, so the review question is always "does this break a rule?", never "would I have written it this way?".
Revisit the document twice a year. Voice should change deliberately, when positioning changes, rather than drifting one caption at a time. Related material sits in the caption writing workflow and the content approval workflow.
Common questions
Can voice differ by platform?
Yes, in register — shorter and more casual in stories than in long captions — while the underlying rules about claims and vocabulary stay fixed.
Who owns the voice document?
Whoever owns positioning. If it sits with whoever writes most, it will drift toward that person's natural style.
How long should it be?
One or two pages. Long guides are not read, and an unread guide has no effect on tone. See about for context on SmmDad.
How do we handle a writer who keeps breaking the rules?
Check first whether the rule is actually right. Repeated breaches by a capable writer often signal a rule that does not survive contact with real captions, rather than carelessness.