If versus whether: separate the condition from the question.
A condition determines when an action applies. An indirect question identifies something to establish. My recommendation uses “if” for the first job and “whether” for the second.
By Adam Frick · First draftIf rain starts, we will move indoors.
We need to know whether rain will start.
A short instruction can leave the reader unsure about the required response. A writer may want confirmation either way, while the reader understands that a reply is needed only under one condition. The choice between “if” and “whether” can help separate those meanings. I recommend “whether” for an unresolved question and “if” for a condition.
See “whether” doing a real job.
You must refer to document verification and the Knowledge Base when deciding whether to accept a digital overseas civil registration document.
The published instruction identifies a decision between acceptance and non-acceptance. The word “whether” introduces that unresolved choice. This example is already a useful model, so a rewrite would serve no necessary purpose. The quoted passage illustrates grammar rather than providing a complete account of passport policy.
Decide what response you need.
Tell me if the room is available.
Tell me whether the room is available.
Contact me only if the room is available.
The first sentence commonly functions as an indirect question about availability. Depending on context, the same wording can also be understood as a conditional instruction to report an available room. The second sentence asks for the answer to the availability question. The third explicitly limits contact to the positive case. These revisions express different intentions, so neither should replace the original until the writer has chosen the intended instruction.
For a booking request, that difference can affect what happens next. A reader who understands a condition may remain silent when the room is occupied. A writer who expects an answer either way may interpret that silence as a missed message. The distinction gives the instruction a more dependable structure, although no single word can remove every contextual uncertainty.
Recognise the accepted alternatives.
Cambridge’s grammar guidance permits both words in many indirect yes-or-no questions. My recommendation is narrower than that description of accepted usage. I teach the distinction because a consistent allocation of jobs can make an instruction more explicit. I do not treat every indirect question with “if” as a grammatical mistake.
Some constructions also favour “whether” for grammatical reasons. Before a to-infinitive, use a form such as “The team must decide whether to proceed”. The phrase “whether to proceed” names the choice awaiting a decision. A mechanical substitution of “if” would not work in that construction.
Review a request containing “if”. Decide whether you need an answer to a question or an action under a particular condition. Choose wording that makes the expected response explicit. If the distinction affects a deadline, add the deadline rather than expecting the conjunction to carry the whole instruction.