CENSUS investigators are taking to the streets of Thorne and district targeting households who have not filled in the questionnaire.
People who refuse to fill in the Census face up to £1,000 fine.
Non-compliance staff will begin conducting interviews under caution with householders who refuse to fill in their form.
Since Census Day, letters and cards reminding people that returning the questionnaire - is required by law have been posted to households where there is no record of a form having been returned.
Forms can be returned in the pre-paid envelope or via www.census.gov.uk