Excessive Growth of the Beak:
Periodically thin splinters will chip off the tip of a budgies beak. This is a normal part of the renewal of the beak's tissue. But in older budgies, for reasons as yet unknown, the beak sometimes grows too fast in spite of frequent whetting. Usually only the upper mandible is affected, but more rarely the upper and lower mandibles cross each other because they both grow too long simultaneously. In either case the bird has difficulty in eating its food. If nothing were done to help, eating would eventually become impossible, and the excessively long beak would injure the skin of the crop region. Don't let things get that far. The best thing to do is to take the bird to an experienced avian veterinarian, breeder, or pet dealer to have the beak trimmed with proper (nail) clippers. If the bird has a predisposition for excessive beak growth, regular trimming may be necessary, sometimes as often as every four weeks. Competent bird owners can quickly learn to perform this duty themselves and dispense with the trips to, the veterinarian. If in spite of all your caution the trimming should result in minor bleeding, apply styptic cotton to the beak until the blood stops. If the beak is very brittle, dab it with slightly warmed glycerine or olive oil before wielding the clippers.
Overgrown beaks are well known among adult like adult parrot-like birds. Most develop because of an incomplete diet. Lack of minerals as found in green food and suitable grit, combined with a vitamin and protein deficiency are usually to blame. Prolonged periods of diarrhoea can result in an overgrown beak by washing out necessary food elements and beneficial bacteria, although this is uncommon.

Every now and then budgies need their beaks clipped. They usually do a fair job of keeping it down themselves and don't need our help.
It takes a lot of practice and a very steady hand to clip the beak of such a small bird. Clipping it too short and not only will you cause it to bleed and bleed and bleed, but you'll traumatize the poor bird and cause it a great deal of pain. Not clipping the beak in the proper manner could also cause the beak to split in older birds or ones in poor health that have low calcium problems and weak beaks.
Here you can see how long the beak is of my eldest budgie, Peanut (he'll be 10 this year!):
Notice I don't clip the beak from the sides. You wouldn't clip your fingernails from the sides, you'd clip them horizontal to the tip of your finger. That's exactly how I clip a bird's beak. The tip of the beak to the red line is the "safe zone" where no blood will come out when I clip it. Any higher and you run the risk of undue injury. You want to clip the beak at about the length of where a normal beak would be.
Many thanks to Kim for offering me the use of her beak pictures and beak cutting guide. -
Kim Clifton-Seminole, Florida USA
Overgrown Claws: