While frozen beef is safe indefinitely, thawing is a little more tricky.
Perishable foods should never be thawed on the counter, or in hot water and must not be left at room temperature for more than two hours. Even though the center of the package may still be frozen as it thaws on the counter, the outer layer of the food could be in the "Danger Zone," between 40 and 140 °F — temperatures where bacteria multiply rapidly.
There are three safe ways to thaw beef: refrigerator thawing , cold-water thawing, and microwave thawing.
This is the best method because it keeps beef at a safe temperature during thawing: at or under 40 degrees F.
Small amounts of frozen beef such as one pound of ground beef or 8 - 16oz steaks require about 24 hours in the refrigerator to thaw. Stick them in the 'fridge the day before in morning or evening and they'll be ready by dinner time the next day! Larger items such as roasts require at least 36 hours for every 5 pounds of meat.
In the case that your dinner plans change, beef remains safe and high quality in the refrigerator for 3-5 days after thawing, and if your plans REALLY change, beef thawed in the refrigerator can be refrozen without cooking.
Cold Water Bath
If you're short on time or forgot to take your beef out of the freezer in the morning or the night before, you may choose to thaw it quickly in a cold-water bath.
Make sure it's sealed in a leak-proof plastic bag, and submerge the bag in cold tap water, changing the water every 30 minutes.
Small packages of beef may thaw in an hour or less, while roasts may take up to 3 hours. Do not refreeze foods thawed by the cold water bath method without cooking.
If you choose to thaw your meat in a microwave, think of it as part of a pre-cooking process. Plan to cook your meat immediately after thawing because some areas of the food may begin to cook during mircrowaving. Do not place microwaved beef back in the refrigerator because there will very likely be portions of the beef that has reached optimal temperatures for bacteria to grow. Always cook immediately after thawing in a microwave. Foods thawed in the microwave must be cooked before refreezing.
It is perfectly safe to cook meats from the frozen state, but remember that cooking will take approximately 50% longer than the recommended time for fully thawed or fresh beef.