This is a fun idea to play around with. Secondary houses can be found by counting the same number of houses away from a house as that house is from the first house. For example, the 7th house is the 10th house from the 10th, so the 7th house is a secondary 10th house, and carries some of the same meaning. In that way, the 7th house can be important to look at for career. This makes sense because careers are mostly built on relationships, and you want to look at the 7th anyway for business partners, customers, and the public in the case of politicians or public figures. Here are the secondary houses. I'm not going to analyze all their meanings, I'm going to let you play around with that!

The secondary house is listed after each house. You'll notice that in some cases, a single house will be a secondary house for two other houses, which means that it really carries the meaning of three houses (if you include itself)!

1st house - no secondary house (everything originates in the 1st and returns to the 1st)
2nd house - 3rd house (2nd from 2nd)
3rd house - 5th house (3rd from 3rd)
4th house - 7th house (4th from 4th)
5th house - 9th house (5th from 5th)
6th house - 11th house (6th from 6th)
7th house - 1st house (7th from 7th)
8th house - 3rd house (8th from 8th)
9th house - 5th house (9th from 9th)
10th house - 4th house (10th from 10th)
11th house - 9th house (11th from 11th)
12th house - 11th house (12th from 12th)