I don't think there is one definitive "most common" way. It's quite context based. Although you will probably almost always be fine with just saying "tack så mycket" or just "tack". It's quite a plain word in and of itself, so it depends a lot on how you say it too. Tone of voice, facial expression, body language and so on. If you want to sound a bit more posh or "sophisticated" you can add things like "tackar ödmjukast!" (my humblest thanks) or "tack så hemskt mycket!" (thank you so terribly much) and so on. In informal contexts, such as when among friends, it's quite normal to combine "tack" with some adjective describing what you think of the person you are thanking or how their assistance/favor helps you. Some examples: "snällt" (kind), "schyst" (kind, more colloquial), "bussigt" (kind, kind of old/outdated), "fint" (great/nice). Can be prefixed with "jätte-" to emphasize. It's kind of how you often say "great, thanks!" in English. Of course, the adjective used largely dictates the tone of the message. Other than that, there are some set thank you phrases used in special occasions: Tack för senast - Giving thanks for the last time you met, used when meeting someone for the first time after you were together at a social gathering or the likes. Tack för maten - Said upon finishing a meal. Said to whoever made the meal for you (although it isn't really used to, say, personnel in a restaurant, more so when a friend made you food. Children are taught to say this after every meal at home too. Tack för idag - Sometimes said at the end of a school- or work day. Basically just "thank you for today". Can be used in a few other cases as well. Tack på förhand - You seem to be familiar with this one already :) For curious people who are reading, means "thank you in advance". I probably forgot a whole bunch of things, but this should get you started at least, good luck! :)