1. Casual filler words (e.g., "ngai" / "na")

These conversational particles add a friendly tone in speech but are inappropriate in written formal Thai. Alternative: Simply omit them, or use proper conjunctions like "therefore" or "accordingly."

2. Slang shortenings

Abbreviated versions of words commonly used in chat or social media should be written out in full. Alternative: Always spell out the complete word in official documents.

3. "OK" and other English loan-slang

While widely understood, "OK" is too casual for formal writing. Alternative: Use "agreed," "acknowledged," or "approved" depending on context.

4. Vague quantifiers ("around," "about")

In formal writing, precision matters. Vague quantities reduce the authority of your statement. Alternative: Use exact numbers or the formal Thai equivalent of "approximately."

5. Casual connectors ("so then," "and then")

Informal conjunctions disrupt the professional flow of a document. Alternative: Use "consequently," "subsequently," or "furthermore."

6. Overly direct commands

Blunt imperative statements can seem rude in formal contexts. Alternative: Frame requests using polite constructions, such as "It is requested that..." or "Please be advised..."

7. Emotional expressions

Words that express strong personal feelings or exclamations are too subjective for formal writing. Alternative: Use neutral, objective language to maintain professionalism.

8. Redundant phrases

Repeating the same idea in different words wastes space and weakens your argument. Alternative: Be concise. State each point once with clarity.

9. Personal pronouns in collective contexts

Using "I" or casual first-person pronouns in government or organizational documents is often inappropriate. Alternative: Use the organization's name, "the committee," or "the undersigned."

10. Internet abbreviations and symbols

Emojis, "555" (Thai internet laughter), and social media shorthand have no place in formal documents. Alternative: Express the intended meaning using complete, formal sentences.