General information only — not legal advice. This page was not written by a lawyer. It explains a word in plain words, using official court sources listed at the bottom. It does not tell you what to do in your own case.

What Is an Affidavit? — In Plain Words

Short answer

An affidavit is a written or printed statement made under oath.

That short definition comes from the United States Courts glossary on uscourts.gov.

What that means, word by word

The United States Courts glossary says an affidavit is:

“A written or printed statement made under oath.”

So three parts matter in that definition:

A fuller court glossary definition

The Legal Terms Glossary of the U.S. District Court for the Western District of Texas says an affidavit is:

“A written statement of facts confirmed by the oath of the party making it, before a notary or other officer having authority to administer oaths.”

In plain words, that glossary adds two points:

How is an affidavit different from nearby words?

Testimony

The same Western District of Texas glossary defines testimony as “oral evidence given by a witness under oath.” Oral means spoken. An affidavit, by the definitions above, is written or printed. Testimony, by that glossary, is spoken.

Deposition

The same Western District of Texas glossary defines a deposition as “an oral statement made by a person before an officer authorized by law to administer oaths.” It also says the attorney for the opposing party is notified to attend the deposition, where that attorney may cross-examine the person. An affidavit, by the definitions above, is written. A deposition, by that glossary, is oral.

Declaration

California Courts Self Help — California example only, not national law — describes a declaration, on its Declaration (MC-030) page, as “a statement in writing that you swear under penalty of perjury is true” made to a court.

California Courts Self Help — California example only — also explains, on a page about recording efforts to find the other parent, that a declaration signed under penalty of perjury “is treated the same way as testifying under oath in a court of law,” and that the person “must be truthful and accurate.” That same California page says a declaration is “similar to testimony given in court,” is “required to be signed under oath and under penalty of perjury,” and that “if you lie on the form, you could be fined by the court and/or be subject to time in jail.” Those sentences are that California court's explanation for that California declaration, not a national rule printed here.

This page does not draw a general national line between “affidavit” and “declaration.” The official sources read for this page do not draw that general line either. One California form below uses the two words together for that form only.

One use named in a federal court glossary

The Western District of Texas glossary, in its definition of summary judgment, says summary judgment is a “judgment given on the basis of pleadings, affidavits, and exhibits presented for the record without any need for a trial.” It adds that summary judgment “is used when there is no dispute as to the facts of the case and one party is entitled to judgment as a matter of law.”

That is one court use named in that glossary. It is not a full list of uses. This page does not add uses that the sources read in full did not list.

California example only — Caregiver's Authorization Affidavit

This whole box is one named court's example only. It is not national law. The source is a California Courts form, the Caregiver's Authorization Affidavit, hosted by California Courts Self Help.

That California form says that completing items 1–4 and signing the affidavit is sufficient to authorize enrollment of a minor child in school and to authorize school-related medical care, and that completing items 5–8 is additionally required to authorize any other medical care for the child.

That California form says: “I declare under penalty of perjury under the laws of the State of California that the information above is true and correct.”

That California form also says: “This affidavit (also known as a declaration)” — for that California form.

And that California form says it “does not need to be notarized,” and does not need a court seal or the signature of a court clerk or judge to be valid. That is the rule printed on that one California form. Do not carry it over to other forms or other places.

That California form also warns the caregiver: “Do not sign this form if any of the completed statements above are not true. If you do so, you will be committing a crime punishable by a fine, imprisonment, or both.” That warning is printed on that California form.

A note about USA.gov

USA.gov does not appear to run a general explainer page that defines “affidavit” for readers. Searches for a USA.gov affidavit definition or explainer, made for this page, did not return a USA.gov page covering the word in general. Because of that, this page rests on the official court sources listed below, and every court example is labeled with its court's name.

What this page does not do

General information only — not legal advice. This page was not written by a lawyer. It explains a word in plain words, using official court sources listed below. It does not tell you what to do in your own case.

Sources

Every factual claim on this page traces to one of these official sources, read in full: