Tomato soup freezes well because it doesn't contain any starchy thickeners, but it may separate if you your recipe uses cream. Freezing and thawing properly ensure that your homemade soup tastes as good defrosted as it did fresh.
If you are making the soup specifically for freezing, leave out the cream or milk. You can still freeze leftover tomato soup with cream, using the same methods, but it will require careful reheating to avoid curdling. Hot soup can heat up your freezer, causing ice buildup or condensation. Instead, cool the soup for no more than two hours at room temperature, or until it's cold in the refrigerator. Package it in a tightly sealed, freezer-safe container, and store it in the freezer for up to six months.
The best way to thaw soup is overnight in the refrigerator. If your soup doesn't contain cream, you can defrost it in the microwave. Use the low or defrost setting, and stir the soup every one to two minutes so that it defrosts evenly. Microwave defrosting can cause cream to curdle, so it's best to thaw it in the fridge. If the cream separates, stir it back into the soup with a whisk, and continue to stir as you reheat it over medium-low burner on the stove top.