Go to Filter>Modify Filter>enter a filter name.

A new window will come up called custom filters.

Click Groups>enter a name.

A new window will come up call filter groups.

On the right choose to add for filter conditions.

Category choose forms and schedules

Field choose Form 1040-ES

Compare is

Value Yes

You will then have a new filter on the left side of the client list to use to show only clients with 1040-ES.