I found a nice answer on the Internet. This should be detailed and useful :) ****************************************************************************************** The expression “so far” is used when we’re in the middle of a particular situation. In other words, the situation has started, but it is NOT over yet. We use “so far” when talking about the sitatuion from the beginning of that situation until the present moment. The future is something the person doesn’t know about because it hasn’t happened yet. Here is a timeline to help you understand: start______________________now_________________________end —————so far—————->/—————unknown—————/ For example, if the situation is the weekend, the start is Friday night and the end is Sunday night. Let’s say that now it is Saturday night. A conversation would be like this: A: How is your weekend so far? B: It’s really good so far. If it is Sunday night, the conversation would be like this: A: How was your weekend? B: It was really good. Now let’s say the sitation is a work project. The start is the beginning of the project and the end is when you finish the project. Right now you have completed 40% of the project. At that point, a conversation might be like this: A: What have you done so far with your project? B: So far, I’ve completed writing the report and making a list of potential customers. Let’s say the situation is a presentation that you’re doing, and you’re in the middle of the presentation. At that point you would ask: Does anyone have any questions so far? If you’ve finished the presentation, you would ask: Does anyone have any questions? So, that is “so far”. The expression “until now” is a little different because it is used to indicate that the situation has changed. For example, look at the following two sentences: I’m happy with my new job so far. I was happy with my new job until now. The first sentence means that that person continues to be happy with the job but doesn’t know about the future. The second sentence means that something has happened and that he or she is no longer happy with the job; the situation has changed. Here are some more examples using “until now”: We didn’t have any problems with the project until now. (Now we have a problem.) I really enjoyed that TV show until now. (Now I don’t enjoy the show anymore.) My neighbors were really loud at night until now. (Now they are quiet.) Please take note that when we use “until now”, we use the past tense, but we DON’T use the past tense with “so far”. ******************************************************************************************