California Wants a Copy of Your Merger Filing, Starting January 1, 2027

For any premerger notification filed on or after January 1, 2027, a company with its principal place of business in California must send the California Attorney General a complete electronic copy of its federal HSR form within one business day of the federal filing.

The trigger is the federal filing date. It is not the signing date or the closing date. A deal filed in December 2026 is outside the act, even if the transaction closes after January 1.

California SB 25, the California Uniform Antitrust Pre-Merger Notification Act, became Chapter 3 of the Statutes of 2026 when Gov. Gavin Newsom signed it on February 10, 2026. The act adds a new article to the Business and Professions Code, beginning with section 16780.

Section 16787 states that the act applies only to a premerger notification filed on or after January 1, 2027.

Two California connections can trigger the filing

A person who files a Hart-Scott-Rodino (HSR) form with the federal agencies must also file with the California Attorney General if either of two tests is met.

The first is the principal-place-of-business test. The person must have its principal place of business in California.

The second is a California sales test. The person, or an entity it directly or indirectly controls, must have annual net sales in California of the goods or services involved in the transaction equal to at least 20 percent of the federal filing threshold.

Morrison Foerster and Baker McKenzie put that amount at about $26.78 million, using the federal size-of-transaction threshold that took effect February 17, 2026. The parties are tested separately. In one transaction, only one side may have to file with California.

That check belongs in diligence. Add the headquarters test and the 20 percent sales test to the HSR checklist for every filing party.

California-headquartered filers send more material

A California-headquartered filer must also send a complete electronic copy of the additional documentary material filed federally. The practical step is direct. Prepare the California submission at the same time as the federal set.

A filer that qualifies only under the sales test sends the HSR form first. It sends the additional documentary material only if the Attorney General requests it. The deadline is no later than seven business days after the filer receives the request.

The Archivar Editorial Desk checked the chaptered text of SB 25 as reproduced by CalMatters Digital Democracy against summaries from Gibson Dunn, Morrison Foerster, and Baker McKenzie. The page reproduces several versions of the bill text that differ. An earlier version shows a 2026 operative date and a $10,000 penalty. The desk used only the chaptered block, which shows January 1, 2027 and $25,000 per day.

One summary gave the period for producing additional material as seven days. The chaptered text says seven business days, and the desk used that. The state’s own legislative site refused automated access during the check, so the desk did not read the text there. Readers should confirm the numbers against the official chaptered text before relying on them.

The Attorney General may charge two different fees

The Attorney General may charge a $1,000 fee to a filer under the principal-place-of-business test. The fee may be $500 for a filer that qualifies under the sales test.

The fees go to the Attorney General’s antitrust account, according to a Gibson Dunn summary. The Attorney General may adjust the fees no more than once every five years.

Budget the applicable fee before the federal filing is made. The California deadline leaves one business day for the electronic submission.

Noncompliance can produce a daily penalty

Section 16785 gives the Attorney General a civil penalty of not more than $25,000 per day of noncompliance.

The Attorney General must first provide written notice. The filer then has three business days to cure. If the violation continues after that period, the penalty can accrue daily.

That cure period is short. Calendar it when a written notice arrives, and treat the filing record as time-sensitive from the start.

California’s filing does not stop the closing

The California filing does not suspend closing. Morrison Foerster, Hooper Lundy, and Baker McKenzie describe the law as non-suspensory.

The Attorney General cannot use this filing to hold a deal in the manner of a federal second request. The chaptered text itself says nothing about a waiting period. The non-suspensory characterization comes from the law-firm summaries.

The law also does not replace separate notice required by California’s Office of Health Care Affordability (OHCA) for health care transactions. Check for OHCA notice separately on a health care deal.

The filing is confidential, but sharing is permitted

Section 16783 bars the Attorney General from making the filing public. The materials are exempt from the California Public Records Act.

The Attorney General may disclose the materials in an administrative or judicial proceeding subject to a protective order.

Gibson Dunn and Morrison Foerster also say the Attorney General may share with federal enforcers, including the Federal Trade Commission and the Department of Justice Antitrust Division. Section 16784 covers sharing with the attorney general of another state that has adopted the uniform act, or an equivalent law with comparable confidentiality protections.

Before sharing with another state under that reciprocity provision, the Attorney General must give the filer at least five business days’ notice. Confidentiality is statutory, but it does not bar every intergovernmental disclosure.

A one-business-day clock can start after hours

California is the third state to enact the uniform act. Washington and Colorado enacted similar laws in 2025. Colorado enacted S.B. 25-126, and Washington enacted S.B. 5122.

The clock also creates an intake problem. Archivar is an AI operating system for a law firm. It answers every call 24/7 in English and Spanish, runs intake, manages matters, and remembers everything the firm does. A client’s call saying the federal filing just went in is answered at any hour, and in Archivar it sits on the matter record with the time of the call. The firm sees the start of the clock when it opens the matter.

Before January 1, 2027, revise the HSR checklist. Test every filing party for a California headquarters and the 20 percent sales threshold. Calendar one business day from the federal filing date. Prepare additional documentary material with the federal set for California-headquartered clients. Budget the correct fee, confirm whether the filing occurs on or after January 1, and check OHCA notice separately for health care deals. If written notice of noncompliance arrives, calendar the three business day cure period immediately.