If I have been contributing to mutual fund for 6 years and decide to sell all, how do I separate long-term capital gains from short term capital gains from the last year?

[SweetieJean]

Hopefully you have been keeping good records. See this:

The Basics of Determining Taxes on Mutual Funds (investopedia.com)

[Mike9241]

shares held for 1 year or less are short-term so you need to look at your records of purchases. but it's required that the mutual fund will send you a 1099-B perhaps it will break down the long and short term portions

[Hal_Al]

Your mutual fund company (almost certainly) will do that for you. It will be separated on the 1099-B forms that send you. They are required , by law, to do that. 

[fanfare]

@sqdillon 

did you look at your 1099-B?

it will say "short term - report with Box A checked".

"long term - report with Box D checked".

This is required of the fund company for shares purchased after 2013 ( or thereabouts).