Checklist for Biur Maasros:[1]

1. The due date for Biur Maasros is customarily on Erev Yom Tov of Pesach of the 4^th and 7^th years of Shemitah. From the letter of the law it is to be done by Erev Shevi’i Shel Pesach, the 20^th of Nissan which is the 6^th day of Pesach, however the custom is to do so by Erev Pesach, the 14^th of Nissan. One who did not do so on Erev Pesach is to do so on Erev Shevi’I Shel Pesach, as is the letter of the law. The following is what is required to be done by this date:
2. Make sure that all produce [i.e. fruits, vegetables, grains] which requires Terumos and Maasros have had all their tithes removed from them.
3. Make sure that all dough’s/breads that need Hafrashas Challah have their Challah removed from them.
4. Make sure that all tithes, Terumos and Maasros [Rishon, Sheiyni and Ani], have been properly distributed, or destroyed.
5. The Maaser Sheiyni coin is to be destroyed or redeemed onto a Peruta worth of fruit such as a Peruta worth of sugar, and then that fruit/sugar is to be destroyed.

[1] See Michaber Y.D. 331:140-146; Rambam Hilchos Maaser Sheiyni 11; Admur 430:3 “As this Parsha discusses the bringing of the tithes to the storehouses, which is similar to what occurs on Erev Pesach, being that on Erev Pesach is the time of Biur. As on every Erev Pesach of the 4th and 7th year of the Shemitah it is an obligation upon every person to remove from his house all of the Maaseros of grains that he tithed in the past three years of Shemitah and that have remained in his house. On this Erev Pesach, he is obligated to remove it from his house and bring it to the house of the Levites. (Now, although there are those who say that the time for this obligation is not on Erev Pesach but rather on Erev Shevi’i Shel Pesach, and so is the main Halachic ruling as brought in Y.D. 331:144, nevertheless, the widespread custom is like the former opinion.)”; Kitzur SHU”A Mitzvos Hateluyos Baretz 12; Hakashrus 15:41