What does Hinduism say in regards to suicide? Or maybe even assisted suicide? Not just out of depression or anger, but what if your just tired and want to retire?
As per the scriptures, one who commits suicide becomes a ghost:
udbandhanamṛtā ye ca viṣaśastrahatāśca ye
ātmopaghātino ye ca viṣūcyādihatāstathā [GP - 2.22.8]
One who dies by hanging, also through poison and weapon, one who commits suicide and also dies by cholera etc. becomes a ghost.
The scriptures also prohibit to perform any funeral rites (shradha) for people who have died by committing suicide and the relatives do not become unclean by such deaths unlike other natural and legitimate deaths.
Suicide is classified as a bad death in Hindu scriptures.
Sri Krishna said, 'O Garuda, hear, I shall tell you the great secret about the rite of death for those who dies through serpent ...; those who commit suicide or die by fall from a tree, ........ All these deaths are known as bad deaths where no rite of Aurdhvadehika or pinda-dana is performed. If the same is done by mistake it is all destroyed in the air. But desiring welfare of the deceased and out of fear of the people's reproach his sons or grandsons or sapindas should perform Narayana Bali, O bird. By that the relatives of the deceased are purified. This is stated by yama. There are no other means. When Narayana Bali is performed they become fit for aurdhvadehika.'
Garuda Purana, Dharma Khanda, Chapter IV.
Suicide is not allowed because it interferes with a person's reasons for staying in the worldly plane. He will have to come back again and again to the worldly plane to complete his education if he commits suicide.
Suicide is allowed for a person who has attained Moksha. I am posting here a quote from Sri Ramakrishna on suicide:
'Suicide is a heinous sin, undoubtedly. A man who kills himself must return again and again to this world and suffer its agony. But I don't call it suicide if a person leaves his body after having the vision of God. There is no harm in giving up one's body that way. After attaining Knowledge some people give up their bodies. After the gold image has been cast in the clay mould, you may either preserve the mould or break it.'
The Gospel of Sri Ramakrishna,Chapter 7, The Master and Vijay Goswami, December 14, 1882
I heard about "kapaala moksham" which means salvation of the skull. There are some legends about really really advanced yoga practitioners, capable of letting their "life" come out of their body by perforating the skull - just through their will, while meditating. Most of these legends also say that those yogis are well aware of the time when they should end their lives. And when their time comes, they achieve this kapaala moksham.
According to Sri-M darshan(Vol 7)
In the Vedas, it is mentioned that for the Jnanis, the following ways of leaving body are accepted: Jumping from above, fasting, diving in river, entering into fire or going to the hills : viraadvane va annshake vaa apaam praveshe agni-praveshe va mahaaprasthaane va.
Sri Totapuri, the vedanta-guru of Sri Ramakrishna, wanted to die by getting drowned in the ganges,but failed. Another spiritually elevated boy Vishnu killed himself by cutting his throat by knief, as mentioned in Sri Sri Ramakrishna-Kathamrita.He was not able to live in the world full of worldly people any more.
But for a normal individual, suicide is a grave sin and his/her ghost suffers tremendously.
Reference: a) Sri Sri Ramakrishna-Kathamrita, By Sri -M, b) Sri M darshan, vol 7(quoted in Sri Sri Totapuri-Prasanga, published by the Lake Kalibari, ISBN 978-81-935349-1-5)