from English Grammar Today. We use if to introduce a possible or unreal situation or condition. We use when to refer to the time of a future situation or condition that we are certain of: You can only go in if you've got your ticket. When I'm older, I'd love to be a dancer. Compare. At the start of a sentence, use a comma after "if necessary", "if needed", "when required", "where needed", etc. Normally, we don't need a comma before "if necessary", "when needed", etc. in mid-sentence or at the end of the sentence. Merriam-Webster unabridged. The meaning of IF NECESSARY is if it is needed. How to use if necessary in a sentence. 1. Vaultboy2403. • 3 yr. ago. When necessary. Alaricos. • 3 yr. ago. Depends 1. IrishBard. • 3 yr. ago. As I'm sure you know, "when necessary" would normally focus on the time, "where necessary" on the place. Restaurant Dinner Reservations Necessary? 10:15 pm. Paris Hotels - adult with 2 young kids 9:30 pm. Boutique Hotel question 9:09 pm. Day Trip to Fontainebleau 9:07 pm. Trip report, October 2023 8:23 pm. Online Tickets Sold out for Musee d'Orsay 8:06 pm. 8. I would say, in my experience as a native British English speaker, that "if needed" would be the most usual, and "if necessary" slightly stronger or more formal. "If it's needed" would actually be quite unusual, less common than "if it's necessary". See Ngram: Share. Improve this answer. Follow. edited Feb 13, 2019 at 19:13. Virtuous Legend. The phrase " if need be " is a fixed phrase and I'd use it to mean " if necessary " or " if needed ". For the purposes of the letter you're describing, it seems to me that you should stick with saying " if necessary " or " if needed ". Those phrases are quite standard and I see no reason not to use them in a formal letter. Scientists at COP28 Say Carbon Removal Fast Becoming Necessary. If the use of fossil fuels doesn't plummet, the world could be forced to rely on expensive technologies that haven't been proven QHz4TO7.