Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE customers ( customer_id VARCHAR, customer_name VARCHAR )
TABLE: CREATE TABLE customer_contact_channels ( active_to_date INTEGER, customer_id VARCHAR )

### Question ###
What is the 'active to date' of the latest contact channel used by 'Tillman Ernser'?

### Accurate SQL ###

SELECT MAX(t2.active_to_date) FROM customers AS t1 JOIN customer_contact_channels AS t2 ON t1.customer_id = t2.customer_id WHERE t1.customer_name = "Tillman Ernser"