ONS has invited 100,000 households across 7 local authorities to take part. Randomly-selected households across the rest of England and Wales are also involved.
Most of these households received an ONS letter in late March asking them to complete an online questionnaire. Anyone invited can visit www.census.gov.uk and use the unique access code in the letter to take part.
ONS has also sent paper versions of the questionnaire to a small number of the households nationwide. People who get one of those can either use the paper copy or go online to fill it in.
Census test day itself is 9 April, but households can complete the questionnaire as soon as they receive their invite. By taking part, they’ll help to shape the 2021 Census.
People invited to take part in the test can visit www.census.gov.uk to fill in the online questionnaire or get more information. ONS also has a census helpline available to offer support – the number is 0300 068 3001 (Welsh language helpline: 0300 123 4591).