Think have just located the source of the problem
In the Information Worksheet Part IV
Mandatory Electronic Payments:
Client is required to make CA tax payments electronically is checked
Now I need to determine why that is checked
The current tax returns certainly does not meet the mandatory epay requirements
But maybe once you are required to epay all future pmts must be paid via epay
Taxpayer is required to pay this and all future payments electronically is "Your estimated tax or extension payment exceeds $20,000"
Or if CA tax liability exceeds 80k
In this case the liability is 23k which is less that the 80k but more that the first 20k rule
Since ProSeries checked that mandatory epay box on its own, I now assume the 20k rule applies to the annual estimate requirement and not just each individual estimate payment