Atmakaraka is the planet which occupies the maximum angle in a sign.Hence the planet which is occupying 29 or 59 or 89 etc are the atmakaraka planet.if there are no planets at 29 degrees then we can take 28 or lesser.In short it should be the maximum degrees in a rasi

Definition:Karakamsa is composed of two words – (1) ‘karaka’ referring to the atmakaraka specifically and other charakaraka (temporal signficators) as well and (2) ‘amsa’referring to the navamsa and other divisional charts. Karakamsa refers to the navamsa (and/or other divisional charts) where the atmakaraka is placed and such asign is treated as the karakamsa-lagna or seat of the real self, the soul and the first house for determining all things connected to deep inner desires and creation cause itself.The sign/navamsa occupied by the ätmakäraka gives us a clue as to the desire of the ätma and the nature of the ätmakäraka gives us vital information about the nature of the ätma, its spiritual development etc.

Some of my experiences are listed below:

1. If a malefic planet is the ätmakäraka, it indicates a high level of spiritual development whereas a benefic planet as the ätmakäraka indicates a relatively lower level. Example: Rahu was the ätmakäraka for Srila Prabhupada and Ramakrishna Paramhamsa.
2. The ätmakäraka invariably indicates suffering during its Vimsottari dasa, especially if a malefic. During the Näräyana dasa of the sign occupied by the ätmakäraka or those aspecting it, great achievements are made. If the native is spiritually inclined then the dasa of the ätmakäraka can be beneficial.
3. A retrograde ätmakäraka indicates a deep-rooted desire as being the cause of thebirth. This has to be seen from the nature of the planet which becomes the AK. For example, if Mars is AK and retrograde, then there is a very strong desire related to succeeding in some battle or competition in this planet and the native will be dragged into innumerable fights and will be fighting all the time. The solution lies in finding the best self defense strategies based on Kärakämsa of which,Ahimsa is the greatest.

Similarly, if Saturn is the retrograde AK then the desire would manifest in the native doing something related to the elders or old knowledge in new bottles. When retrograde, this desire is very strong and will be the cause of all direction in life. The other signification of Saturn is sorrow and if the native gives sorrow to others, especially elders and those who are like Guru, then know that he is running a bad time and a lot of sorrow is in his destiny (in any case). The best remedy for him would be to develop a stoic attitude towards the acts and words of others and keep prodding in his path. In this manner, the retrogression is to be understood.

4. Combustion of AK gives spiritual insight.

Planets as ätmakäraka:

1. Sun as AK indicates the native has to learn to overcome his ego and should become humble.
2. Moon as AK indicates that the native should be very caring and compassionate.
3. Mars as AK indicates that the native should refrain from all forms of violence and stick to the path of Ahimsa.
4. Mercury as AK indicates that the native should control his speech and be truthful at all times

.5. Jupiter as AK indicates that the native should always respect the Guru, husband and care for children.

6. Venus as AK indicates that the native must have a very clean character and refrain from illegitimate sex/lust.
7. Saturn as AK indicates that the native cannot give sorrow to others and willhave to share the sorrow of many others.
8. Rahu as AK indicates that the native maybe cheated often and will still haveto be free from guile and clean hearted.