The 10-Q and the 10-K are the two backbone periodic reports U.S. public companies file under the Securities Exchange Act of 1934, and the difference between them comes down to three things: how much of the year they cover, whether the financial statements are audited, and how much detail they carry. The 10-Q is the quarterly report; the 10-K is the annual report. A company files three 10-Qs and one 10-K each fiscal year, and understanding why there are exactly three 10-Qs is the fastest way to grasp how the two fit together.

The form's own instructions are explicit about its purpose and cadence. The SEC's Form 10-Q General Instructions state:

"Form 10-Q shall be used for quarterly reports under Section 13 or 15(d) of the Securities Exchange Act of 1934... A quarterly report on this Form... shall be filed within the following period after the end of each of the first three fiscal quarters of each fiscal year, but no report need be filed for the fourth quarter of any fiscal year."— SEC Form 10-Q, General Instructions, source

That single instruction explains the structure. There is no fourth-quarter 10-Q because the fourth quarter is reported inside the annual 10-K, which covers the entire fiscal year. So the rhythm of disclosure for a calendar-year filer is: a 10-Q after Q1, a 10-Q after Q2, a 10-Q after Q3, and then a 10-K that closes out Q4 and the full year. A reader who wants a company's fourth-quarter figures derives them by subtracting the three reported quarters from the annual totals in the 10-K, because no standalone Q4 report exists.

Audited versus unaudited, and the scope gap

The most consequential difference is assurance. A 10-K contains audited financial statements — an independent registered public accounting firm has examined them and issued an opinion. A 10-Q contains unaudited interim financial statements; they are subject to a more limited review by the auditor rather than a full audit. That is why a 10-K is the document analysts treat as the authoritative annual record and why year-over-year comparisons and risk analysis lean on it. The interim 10-Q is faster and lighter precisely because it is not put through a full audit each quarter.

Scope follows from that. The 10-K is comprehensive: it carries a full description of the business, a complete risk-factors section, management's discussion and analysis (MD&A) for the full year, audited financial statements with footnotes, and governance and compensation context. The 10-Q is an update, not a fresh full picture. It presents the quarter's condensed financial statements, an MD&A focused on what changed since the last annual report, and material updates to items like risk factors and legal proceedings — but it does not re-state the entire business description from scratch. A practical way to think about it: the 10-K establishes the baseline once a year, and each 10-Q reports the deltas against that baseline for the next three quarters.

The filing deadlines

Timing differs as well, and the form instructions set the 10-Q clock directly. A quarterly report on Form 10-Q is due, per the instructions, "40 days after the end of the fiscal quarter for large accelerated filers and accelerated filers" and "45 days after the end of the fiscal quarter for all other registrants." The 10-K deadline is longer because the annual report requires a completed audit: it is due 60 days after fiscal year-end for large accelerated filers, 75 days for accelerated filers, and 90 days for all other filers. Those filer categories — large accelerated, accelerated, and non-accelerated — are defined by public float and revenue thresholds in the SEC's rules, and they determine both sets of deadlines.

For a reader trying to follow a company through the year, the deadlines also explain the disclosure calendar. After each of the first three quarter-ends, expect a 10-Q within about six weeks; after fiscal year-end, expect the more detailed 10-K within two to three months. Earnings press releases typically come out before either form is filed and are furnished separately on a Form 8-K; the 10-Q or 10-K is the complete, formal filing that follows, and it is the document that carries the footnotes, the full statements, and — in the annual case — the audit opinion.

Both forms also carry executive certifications and internal-control disclosures, but at different depths. Each 10-Q and 10-K includes certifications signed by the principal executive and financial officers attesting to the report's accuracy and to the design and operation of disclosure controls. The annual 10-K goes further: it contains management's annual report on internal control over financial reporting, and for larger filers an auditor's attestation on those controls — neither of which appears in a quarterly 10-Q. So the 10-K is not just a longer 10-Q; it adds the audit opinion on the financial statements and, separately, the controls framework that the interim reports update against rather than re-establish.

The grounded way to use the distinction is to match the question to the right form. For audited, full-year figures, the durability of the revenue base, the complete risk-factor set, and the audited cash-flow statement, read the 10-K. For what changed this quarter, the most recent interim balance sheet, and updated risk or litigation disclosures, read the 10-Q. Both are primary sources filed on EDGAR, both are searchable by company, and both state on their face which period they cover and whether the financials are audited. When in doubt about a number's pedigree, the form type tells you immediately whether you are looking at an audited annual figure or an unaudited quarterly one — and that pedigree is exactly what the form's own instructions are designed to make unambiguous.