Arigatou gozaimasu or Arigatou gozaimashita

It’s a question I sometimes get asked not only by beginners, but also by advanced students. 

What’s the difference between “arigatou gozaimasu” and “arigatou gozaimashita”? 

The answer is simple, but I’ll write it out to make sure you understand it. 

“Arigatou” expresses gratitude. You say it when someone has done something for you—for example, if your boss helped you with something at work. 

“Tetsudatte kudasatte, arigato gozaimashita.” 

The past tense “gozaimashita” is used because your boss had already helped you before you said it. This is logical, isn’t it? 

However, the present tense “arigatou gozaimasu” can also be used in this case. That’s why these expressions cause confusion. 

 Consider this next example. Let’s say your client is going to prepare some documents for you by next week. 

“Arigato gozaimasu. Yoroshiku onegai shimasu.”

The present tense is used because your client hasn’t prepared them yet. In this case, you can’t use the past tense. Remember: The past tense can’t be applied to incomplete events. This is a rule!