Taxes on Sale of Property Held for less than 1 year

[Michael R.]

I have a few properties I am going to sell. One I have owned almost one year the other 3 I have owned less than one year. They are great properties but I just wanna sell and clear up some debt I have and put myself in a more secure position. I have heard from other investors as well as my accountant that I should hold the properties for more than one year to pay less taxes on the sale. I never asked my accountant why (well maybe i did but i forgot) because I was not planning to sell at the time. So is this true and if so what is the reason?

Also another question is if I sell and finance the sale do I have to pay all of the taxes on the sale up front in the year I sell the property? Or do I just pay taxes in the year the payments are recieved?