Motion to Tax Costs Deadline in California: 15-Day Rule and Service

In California, the deadline to file a motion to tax costs is 15 days after the prevailing party serves you with a Memorandum of Costs, under California Rules of Court, Rule 3.1700.1Judicial Branch of California. California Rules of Court 3.1700 – Prejudgment Costs That window stretches by a few days if the memorandum was served by mail or electronically, but the base period is short and unforgiving. If you let it pass, the court clerk adds the full claimed amount to the judgment without any review.

When the Clock Starts

The 15 days run from the date the Memorandum of Costs is served on you, not the date you open the envelope or the email. If the memorandum sits unread for a week, half your time is already gone. Service is a legal event tied to what the prevailing party did, not what you noticed.

The memorandum itself is filed on Judicial Council form MC-010, verified under penalty of perjury by the prevailing party that the costs listed are correct and were necessarily incurred.2Judicial Council of California. California Judicial Council Form MC-010 – Memorandum of Costs (Summary) That verification carries weight at the hearing, but it does not make the numbers untouchable.

How Service Method Changes the Deadline

The base 15 days get extended depending on how the memorandum reached you. The extensions come from the Code of Civil Procedure:

Court days and calendar days are not the same thing. The five-day mail extension counts weekends and holidays. The two-day extensions for express delivery and electronic service count only days the court is actually open. If the final day of your deadline falls on a weekend or court holiday, it rolls to the next business day under CCP § 12a.

Calculate the date the moment the memorandum arrives. Write it down. Do not calculate it later.

What the Motion Must Actually Say

A motion to tax costs is not a general complaint that the bill looks high. Rule 3.1700(b) requires you to identify each item you challenge by the same number and in the same order it appears on the Memorandum of Costs, and to explain why that specific item is objectionable.1Judicial Branch of California. California Rules of Court 3.1700 – Prejudgment Costs The motion goes line by line, or it does not do its job.

The usual grounds for striking or reducing a line item are that the cost is not on the allowable list in CCP § 1033.5, that the amount claimed is unreasonable for the case, or that the expense was not reasonably necessary to the litigation.5California Legislative Information. California Code CCP 1033.5 – Allowable Costs Items that commonly show up on memoranda but fall outside the statute, such as general photocopying, private investigator fees, or legal research charges, are strong candidates. You can also move to strike the whole memorandum if the filing party is not actually the prevailing party or missed its own filing deadline. Whether you object to one line or every line, the same 15-day window applies.

Who Has to Prove What

California case law splits the burden in a way that rewards specificity. If the items on a verified Memorandum of Costs appear on their face to be proper charges under CCP § 1033.5, the burden sits on you, the challenging party, to show they were unreasonable or unnecessary. When you make a proper, specific objection that an item falls outside the statute, the burden shifts back to the prevailing party to justify the cost. Vague objections leave the burden where it started. A well-drafted, item-by-item motion changes the shape of the hearing.

What Happens If You Miss the 15 Days

Miss the deadline and you waive your objections. All of them. The clerk then adds the full amount from the Memorandum of Costs to the judgment, without a hearing and without judicial review of whether the items were even allowable.1Judicial Branch of California. California Rules of Court 3.1700 – Prejudgment Costs The claimed costs become part of what you owe.

Relief from a missed deadline is theoretically available under CCP § 473(b), which lets a court set aside a result caused by mistake, inadvertence, surprise, or excusable neglect. Courts treat cost deadlines seriously, and getting relief requires a real reason for the delay, not simple oversight. It is not a plan; it is a last resort with poor odds.

Post-Judgment Enforcement Costs Use a Shorter Deadline

Everything above concerns prejudgment costs, meaning the ordinary expenses of getting through trial. If the case has moved into collection and the judgment creditor is claiming costs of enforcement, a different rule applies. Under CCP § 685.070, the judgment debtor has only 10 days after service of that memorandum to file a motion to tax those enforcement costs.6California Legislative Information. California Code CCP 685.070 – Post-Judgment Enforcement Costs If nothing is filed inside that 10-day window, the enforcement costs are automatically allowed.

The shorter deadline catches people who assume the familiar 15 days apply. If you have been served with a cost claim after judgment, check which statute governs before you calendar anything.

A Practical Checklist

When a Memorandum of Costs arrives, three things need to happen the same day:

  • Note the date and method of service shown on the proof of service. That is what the deadline runs from.
  • Calculate the deadline using the correct extension for the service method, and confirm whether the final day is a court day.
  • Read the memorandum against CCP § 1033.5 and flag any item that is not on the allowable list, appears inflated, or was not necessary to the case.

Everything after that is drafting. The deadline is the part that cannot be recovered.