The tone for most business writing is formal – and that’s non-negotiable. While each company and industry’s culture will be distinct, composing your business documents with an air of formality is always the safe bet.
Informal Writing
Of course, there will be situations in the workplace where casual might be better. Quick IMs and emails to coworkers to discuss unofficial items (such as inviting them for lunch) obviously works better with a relaxed tone. Be wary of casual correspondence when addressing superiors, though – job position does play a part on how “relaxed” you can get.
Keep It Reasonably Formal
There’s a world of difference between being extremely formal and being reasonably formal. Most of the time, being too formal can make your writing sound stilted. Opt for a natural, but respectful tone, the way you would address the president of your organization in a dinner conversation.
Documentations (meant for records, rather than dissemination) are the one area where being strictly formal might be best. For instance, a business contract where less than strict formal language is used can lead to problems later down the line (such as when settling issues in arbitration).
Seek Help
Not sure if your business writing is appropriate for the situation? Use a business-centered writing software, which can help suggest ways to improve your writing to match your specific situation, apart from all the usual correction and checking it performs.

