Large account

Today I sent a estimate for a large commercial account.
Is it good business to require a certain percentage paid up front, and the remainder paid after services are completed?
If so, what percentage?

For us it depends on the situation. With these large jobs we get them frequently from cleaning companies. If thats the case and its our first time dealing with that cleaning company we require 50% on anything over 3 grand. A credit Card deposit helps to. If its direct dealings with a reputable company we usually dont require a deposit, however we do stress heavily we would like a check cut upon completion.

for me i require 25% down before the job starts, on jobs over $2000. I have not run into problems so far.

On the $30,000 job I did, I asked for 40% up front, and they had no problem with it.

Yeah this will be a $4000 potentially $6000 job dealing directly with the customer My biggest so far.
Thanks for the replies. Good to know.