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Yes! You can use AI to fill out Form SUM-300, Declaration of Lost Summons After Service

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Form SUM-300, Declaration of Lost Summons After Service, page 1
Basic · 38/100Form Complexity Index

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What this form asks for

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Form SUM-300, Declaration of Lost Summons After Service, is a mandatory California Judicial Council form used in a lawsuit. It is a sworn statement filed with the court to attest that a summons was properly served on a party, but the original document proving the service has been lost. This declaration is crucial as it provides an alternative proof of service, allowing the legal case to move forward without the original summons. Today, this form can be filled out quickly and accurately using AI-powered services like Instafill.ai, which can also convert non-fillable PDF versions into interactive fillable forms.
Fillable fields59
Pages2
Form Complexity IndexBasic, 38/100

The AI checks your answers before you download

14 checks built for this form, so a wrong date or a missing answer is caught before anyone else sees it.

Case Number Presence

This check ensures the 'CASE NUMBER' field is not empty. The case number is the unique identifier for the legal proceeding in the court system. Submitting the form without a case number would make it impossible for the court clerk to file it with the correct case, leading to rejection of the document.

Valid Date of Service

Validates that the 'On (date):' field under section 2 contains a properly formatted, valid date. The date cannot be in the future, as service cannot have occurred on a day that has not yet passed. This date is fundamental for establishing legal timelines, and an invalid or future date would nullify the declaration.

Manner of Service Selection

Ensures that at least one checkbox from section 7 ('Manner of service', options a-f) is selected. The declarant must specify the exact legal method used to serve the summons. Failure to select a manner of service makes the declaration incomplete and fails to prove that service was executed according to required legal procedures.

Conditional Requirement for Place of Mailing

If checkbox 7a, 7b, 7c, or 7e is selected, this check verifies that the corresponding 'Place of mailing (specify)' field is filled out. The mailing location is a required component of these service methods under the Code of Civil Procedure. Omitting this detail invalidates the claim of proper service by mail or substitution.

Specification for 'Other' Manner of Service

Verifies that if checkbox 7f ('Other') is selected, the corresponding text field is filled with a description of the service method and the authorizing code sections. The court needs to understand the specific, non-standard method used to determine its legality. An empty description for 'Other' makes the declaration ambiguous and legally unacceptable.

Notice on Summons Selection

Confirms that at least one checkbox from section 8 ('The following notice appeared on the copy of the Summons served', options a-c) is selected. This information clarifies the capacity in which the defendant was served (e.g., as an individual or on behalf of a corporation). This detail is legally significant and must be included for the declaration to be complete.

And 8 more checks
  • Specification for Fictitious Name Service
  • Completeness of 'On Behalf Of' Service
  • Party Served Name Required
  • Declarant Information Completeness
  • Logical Declaration Date
  • Plaintiff and Defendant Identification
  • Declarant Phone Number Format
  • Attachment Indication for Specific Service Types

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How to Fill Out SUM-300 Online for Free in 2026

What the AI walks you through.

  1. Navigate to Instafill.ai and upload your SUM-300 form or select it from the template library.
  2. Use the AI assistant to automatically fill in the court information, including the court name, address, and branch name.
  3. Enter the names of the Plaintiff/Petitioner and Defendant/Respondent, along with the case number.
  4. Complete the main declaration section, specifying the date of service, the documents served, and the name of the party who was served.
  5. Select the appropriate checkbox to indicate the manner of service (e.g., Personal, Substituted, Mail) and provide any required details like mailing addresses or dates.
  6. Indicate how the party was served (e.g., as an individual, on behalf of a corporation) and provide the declarant's current address and phone number.
  7. Review all entered information for accuracy, then date and e-sign the declaration before downloading the completed form for filing.

Common Mistakes in Completing SUM-300

The ones the AI is built to catch.

Missing or Invalid Signature and Date
Forgetting to sign and date the declaration under penalty of perjury in section 10 is a critical error. An unsigned or undated form is legally invalid and will be rejected by the court, rendering the entire declaration void. Always double-check that the declarant has physically signed, dated, and printed their name before submission.
Failing to Detail the Manner of Service
Simply checking a box in section 7 is not enough; filers often forget to provide the required supplemental information. For example, they may omit the 'Place of mailing' for substituted or mail service, which is essential for validating the service method. This omission can lead to the service being deemed improper and requires the process to be repeated, causing significant delays.
Ignoring the 'Notice on Summons' Section
Section 8, which specifies how the party was served (e.g., as an individual, a corporation), is frequently left blank. This information is mandatory under the Code of Civil Procedure and explains the legal capacity of the person or entity served. Failing to complete this section makes the declaration incomplete and will likely lead to its rejection by the court clerk.
Improperly Documenting Substituted Service
When using substituted service (section 7b), filers must attach a separate declaration detailing their attempts at personal service first (due diligence). Many people check the box for substituted service but forget to include this mandatory attachment. Without proof of due diligence, the substituted service is invalid, which can be grounds for a defendant to have the case dismissed.
Incorrectly Identifying Entity Service Type
In section 8c, filers must select the specific Code of Civil Procedure section that corresponds to the type of entity served, such as a corporation or partnership. People often guess or select the wrong code, which can legally invalidate the service. This mistake happens due to a lack of legal knowledge and can have serious consequences for the case's progression.
Vague Description of Served Documents
In section 2, filers sometimes write a generic term like 'legal papers' instead of specifying the exact documents served, such as 'Summons and Complaint'. This ambiguity can be challenged and may render the proof of service defective. It is crucial to list every single document that was included with the Summons to create a clear and indisputable record.
Failure to Attach Required Proof
Certain service methods require specific attachments, which are often forgotten. For service by mail (7c or 7e), the filer must attach the signed Acknowledgment of Receipt or the signed return receipt, respectively. Submitting the declaration without this physical proof invalidates the chosen service method, as there is no evidence the defendant actually received the documents.
Inaccurate or Incomplete Case Information
Mistakes in the header section, such as an incorrect case number or misspelled plaintiff/defendant names, are common and lead to immediate rejection. The court clerk uses this information to file the document in the correct case file. Using an AI-powered form filling tool like Instafill.ai can prevent these data entry errors by saving and auto-filling correct case information across all related documents.
Confusing Personal vs. Substituted Service Details
Filers sometimes mix up the details for different service types, creating a contradictory record. For instance, they might indicate personal service (7d) but then fill out section 4, which is only for substituted service. This confusion makes it unclear how service was actually performed and can lead a judge to rule the service as defective. Since many legal forms are only available as non-fillable PDFs, a tool like Instafill.ai can convert them into interactive, fillable versions with guided fields to help prevent such contradictions.

Frequently Asked Questions About SUM-300

 

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This plan is for your SUM-300: your own AI agent fills it as often as 5 times a month. To fill other forms and upload your own, choose a Professional plan from your account.
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How does the AI fill out SUM-300?
You answer a few questions in plain words, or upload a document you already have. The AI reads what you give it and puts each answer into the right field of SUM-300, on every page, in seconds. It checks the answers against the form's own rules, and you review and change anything before you download, print or sign.
What happens to my information?
It is encrypted in transit and at rest, and it is never used to train AI.
How complex is SUM-300 to fill out?
SUM-300 has a Form Complexity Index of 38 out of 100, in the basic tier: 59 fillable fields across 2 pages. Instafill.ai's AI fills it in under a minute, with every field there for you to review before you download.
What is the purpose of the SUM-300 Declaration of Lost Summons form?
This form is used to declare to the court that a summons was properly served on a party, but the original summons document has been lost. It acts as a legal substitute for the lost original, allowing the case to proceed.
Who needs to fill out and sign this form?
The person who served the summons (the declarant) must complete and sign this form. The declarant must be at least 18 years old and cannot be a party to the lawsuit.
Is this form the same as a Proof of Service?
No, this form specifically replaces a lost original summons document. It is often filed along with a separate Proof of Service form to provide the court with a complete record of service.
What information do I need to provide about the service?
You must provide the date of service, the name of the party served, any other documents served with the summons, and a detailed description of the manner of service (e.g., personal, substituted, mail).
What does 'Substituted service' mean in Section 7b?
Substituted service is an alternative method where copies are left with a competent person at the party's home or business, followed by mailing a copy. This method requires you to first attempt personal service with 'reasonable diligence'.
Do I need to attach any other documents to this declaration?
Yes, depending on the method of service, you may need to attach other documents. For example, substituted service requires a declaration of diligence, and service by mail may require an acknowledgment of receipt or a signed return receipt.
How do I complete Section 8 regarding the notice on the summons?
In Section 8, you must indicate how the served party was identified on the summons, such as an individual, a corporation, or a person sued under a fictitious name. Check the box that matches the notice on the copy of the summons you served.
Where do I file the completed SUM-300 form?
Once completed and signed, the form must be filed with the court clerk at the courthouse where the lawsuit was filed. This ensures it becomes part of the official case record.
What happens if I don't file this declaration after losing the summons?
Without the original summons or this declaration, there is no official proof that the summons was ever issued and served, which could lead to delays or dismissal of your case.
Can AI help me fill out the Declaration of Lost Summons form?
Yes, services like Instafill.ai use AI to help auto-fill repetitive information such as court details, party names, and case numbers, saving you time and helping to prevent errors.
How can I fill out this form online if I only have a PDF?
You can use a service like Instafill.ai to fill out the form online. Simply upload the PDF, and the platform will convert it into a fillable format that you can complete on your computer or mobile device.
My SUM-300 PDF is not fillable. What should I do?
If you have a non-fillable or 'flat' PDF, you can upload it to Instafill.ai. The service's technology will automatically detect the fields and convert the document into an interactive, fillable form for you.
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