From the Agency for Cultural Affairs.
The Joyo Kanji Table was set by a Cabinet notice on November 30, 2010. It is a guide to the kanji used for writing modern Japanese in everyday life.
The table has 2,136 kanji. The table before it, from 1981, had 1,945, so 191 were added.
Of the 2,136, children learn 1,006 in elementary school, and they are expected to be able to use them by the end of junior high school.
The Cabinet notice “Modern Kana Usage” (1986) is the guide for spelling words in kana. As a rule, words are written the way they sound in today’s Japanese, with some special cases kept from custom.
The Cabinet notice “Writing Words from Other Languages” (1991) is about writing words from other languages, and foreign place names and personal names, in katakana.
These guides are for laws, government papers, newspapers, magazines and broadcasting. They do not try to control how each person writes, or writing in special fields.
There is no single right answer. Talking it over with someone at home is a good way to learn.