April 1 marks Census Day, a reference date (not a deadline) for being counted.

When filling out a census form, either online, by phone or by mail, the U.S. Census Bureau will ask where you live on April 1, 2020, in order for an accurate population count.

Here is what you need to know about the 2020 census:

An accurate count helps with funding and voting.

The census helps the federal government allocate funding to local communities. According to census.gov, more than 100 services depend on an accurate census response, including school lunches, highway construction and education.

Government officials will also use responses to adjust or redraw electoral districts after this year’s election.

The census is required by the Constitution.

This year’s count isn’t arbitrary — the census was first mandated by the U.S. Constitution in Article I, Section 2 to occur every 10 years. Your response is required by law.

»RELATED: Atlanta identifies, corrects nearly 80,000 addresses before 2020 census

Expect a knock on your door if you don't participate by late May. The Census Bureau plans to hire 500,000 workers to help take the count and to follow up in person when necessary, according to CNN.

The census asks a few demographic questions.

The first question states: “How many people were living or staying in this house, apartment, or mobile home on April 1, 2020?”

The questions following will ask about each person counted in the first question, including their name, sex at time of birth, birthdate, age and race.

There is also an opportunity to list if a person is only there temporarily but usually stays elsewhere for college, business or the military.

You don’t have to be a citizen to be counted.

There is no citizenship question on the 2020 census, and you should respond to the census if you live in the U.S. even if you are a refugee, immigrant, temporary resident or undocumented migrant.

"Everyone living in the United States and its five territories (Puerto Rico, American Samoa, the Commonwealth of the Northern Mariana Islands, Guam, and the U.S. Virgin Islands) is required by law to be counted in the census — whether they are citizens or not." —census.gov

There are multiple ways to be counted.

Note that April 1 is just a reference day, not a deadline for being counted. The Census Bureau collects questionnaires many different ways including online, over the phone, through the mail and in person.

Counts come in on a rolling basis and are due officially by Dec. 31 to the president and Congress.

According to CNN, the census officially kicked off Jan. 21 in the remote village of Toksook Bay, Alaska. Mail service is spotty in that area of the country, so census officials traveled by snowmobile to record the population in person.

The rest of the United States began receiving official mail with how to report for the count in mid-March.

You can see who has responded so far here:

The coronavirus has impacted the census.

Experts note the unprecedented COVID-19 pandemic has vastly altered living situations recently, making it a hard time to count heads.

"If someone such as a college student is just living with you temporarily due to the COVID-19 situation, they should be counted where they ordinarily would be living on April 1, 2020," the census website states.

There’s also the worry that people may simply forget with everything else happening.

"There is the issue of attention. Certainly when folks are anxious about the public health issue, and kids are away from school, and they're being away from work, it's a concern that the census isn't on top of people's mind as you would want it to be," said Thomas Saenz, president of the Mexican American Legal Defense and Educational Fund.

Urban Institute researchers suggest a postponement of the Dec. 31 deadline, according to The Associated Press. This change would require an act of Congress.

“There’s no way reliable counts are going to be generated by the end of December,” said Robert Santos, vice president and chief methodologist at the Urban Institute. “It's implausible.”

»MORE: Census Day arrives with US almost paralyzed by coronavirus

»COMPLETE COVERAGE: CORONAVIRUS