The benefits of registering under an umbrella school are:
"Umbrella schools come in many different shapes and sizes. Many offer a wide range of services to a homeschooling family. Umbrella schools may allow homeschoolers to participate in sports and/or labs, offer annual testing, guidance counseling and more. Some umbrella schools may only serve as a record keeping office for a homeschooling family’s records.
Umbrella schools may dictate the type of curriculum which homeschoolers must use, while others may leave the choice up to the individual families. Some umbrella schools are only offered to families of specific faiths, while others are more flexible with their enrollment guidelines." http://www.mamashealth.com/homeschool/umbrella.asp
Many still allow you to 'design your own homeschool" with your own school name, etc.
They may be accredited for families who don't want questions when entering college.
They can provide student report cards.
They may keep attendance records, or require them.
They may give curriculum guidance or provide curriculum.
You only report to the school and not the state. (The state may make visits to your home.)
They can provide a student ID card.
Some are free, some have fees.
An umbrella school may reduce time spent preparing for teaching, less record keeping.
They also may offer athletic programs, etc. if the location is in your area.
Umbrella schools may offer an official diploma because if you homeschool without an umbrella school or accreditation, colleges may require a dipoma and your child may therefore have to get a GED-which , according to some, looks like they may have dropped out.
Okay, so you have choices depending on where you live. You can register yourself with the state--design your own homeschool--and keep your own homeschool records. Or you can register under an umbrella or cover school with its options. Or you can admit your child under a school with a ready curriculum.