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 Documents_with_expenses (budget_type_code VARCHAR)

### Question ###
What is the budget type code with most number of documents.

### Accurate SQL ###

SELECT budget_type_code FROM Documents_with_expenses GROUP BY budget_type_code ORDER BY COUNT(*) DESC LIMIT 1