If you are getting a translation for business purposes, then the answer is probably yes, as most translation that businesses require does need a specialist. To help you decide, here are two key questions to ask yourself:
1. Would an intelligent 12 year-old child understand this text and be able to rephrase it in a way that meant it was still be suitable for me to use? If a 12 year old could not do this, then you need a specialist. If they could, go to question 2.
2. Are there any special requirements for the end product, such as that it should be suitable to use as subtitles or for dubbing? If the answer to both these questions is no, you do not need a specialist.

What sort of specialist do I need?

For some businesses the answer is simple. If you are a bank and want your annual report translated, you obviously need a financial translator – not only are you getting a financial document translated, the document is about a financial institution, so a financial specialist is obviously correct here.
But what if you’re getting an annual report for a medical devices company translated? Do you need a financial or a medical translator? Here the answer is that you need a financial translator because it is far more likely that specialist terms in your annual report will relate to financial matters (e.g. the balance sheet) than that they will relate to the medical devices.
If in doubt, look for the specialism that the bulk of the text relates to, for instance contracts are full of legal language, but also include some sentences relating to other specialisms such as IT, medical topics or telecommunications. Because there’s more legal language than other specialist language, you need a legal specialist.

How do I find a good specialist?

This is the tricky part. It’s very easy to say you’re a specialist in an area, but difficult to get the experience and knowledge needed to really specialise in a field. Because of this, be wary of any single translator who has a long list of very different specialisms. If anyone says they specialise in finance, law, IT, medical, chemistry and subtitling, be very wary unless they have a very long career history and can show where this experience came from.
It’s different if someone has a long list of very similar sounding specialisms – especially if these would all fit under a single subheading. Someone who specialises in corporate finance, accounting, derivatives, economics and insurance is basically telling you that they specialise in finance and these are the areas of it in which they have particular experience. These topics all relate to each other and you can often gain experience in several related topics from the same source at once.
There are three particularly good sources of experience:
1. Working as a translator with a certain specialism for a long period of time (particularly at a company that specialises in that area and can provide feedback and training).
2. Studying a topic at degree level.
3. Working directly in the relevant industry in a role other than translator (ideally using more than one language).
If you understand the topic you need a translation in and are competent in the target language (the language the document is to be translated into) or both the target language and the source language (the language the original document is written in), then it may be worth asking for a short sample translation, so you can see what sort of work the translator or company is capable of producing.
Do I need a proofreader?