Q – What does it mean if an editor asks you to write an article “on speculation?”
A – It simply means that the editor is interested enough in the topic to take a look at your article, but not interested enough to commit to buying it. That means you have no guarantee that the editor will buy it. In most cases, if you get a go-ahead from the editor when you submit a query, it will be on speculation. In some cases, even if the editor contacts you to write a piece, he can also indicate it's on speculation. That way the risk is all yours. Some writer's refuse to write on speculation, but that would be your choice. Typically, if you are a new writer, you would go ahead and accept those assignments even without the guarantee, in hopes it will be the beginning of a good relationship with that editor.
Even if an editor gives you a firm assignment, he can always reject the final article. If that is the case, many editors will compensate the writer by paying them a “kill fee.” That means they will be paid to the “kill” the article. The kill fee ranges anywhere from 25% to 100% of what they would have received if the article had been published. If you have a contract with the editor concerning this article, it may make reference to the amount of the kill fee, if it comes to that.