Curiosity is getting the better of me:  Are California Estimated Tax payments really funky?

I only have one California client, and ProSeries is producing some Estimated Tax Vouchers.  Taxpayer owes $1678 and the program is producing ES-1 for $341, ES-2 for $455 and ES-4 for $341.  There is no ES-3.

That just seems really weird.

It doesn't really matter because they are increasing their withholding, but it just caught me as really bizarre Estimated Tax vouchers.