What happens if I turn down a project proposal?

On Malt, you aren't required to accept every project that's proposed to you.

If it doesn't match your skills, if your schedule can't accommodate extra work at a specific point in time, or if you simply aren't interested in what's being proposed to you, there is no issue whatsoever with saying "no" to the client.

Whatever you choose to do, don't forget to respond to the client with your decision. Not only is it a respectful thing to do, but it will also ensure that your response rate (as displayed on your freelancer profile) doesn't get negatively impacted.