Is it very difficult to collect a debt if the defendant cannot be served?
<p>Small claims generally do not allow service by publication. If the defendant cannot be found you have to pursue a real lawsuit. This will not be worthwhile unless there is tens of thousands of dollars involved.</p>

<p>According to [this Nolo publication] (<a href="https://www.nolo.com/legal-encyclopedia/free-books/small-claims-book/chapter11-4.html" rel="nofollow noreferrer">https://www.nolo.com/legal-encyclopedia/free-books/small-claims-book/chapter11-4.html</a>): </p>

<blockquote>
  <blockquote>
    <p>In a typical state, substituted service works like this:</p>
    
    <ol>
    <li>Small claims papers may be served by an adult who is not named in the lawsuit by leaving a copy at the person's dwelling place in the presence of a competent member of the household who is at least age 18 (and who must be told what the papers are about) or at the person's workplace during normal business hours with the person in charge (who must be told what the papers are about).</li>
    <li>On the same day, a copy of the papers must also be mailed to the defendant by first-class mail.</li>
    </ol>
  </blockquote>
</blockquote>

<p>You could try that method. </p>

<p>According to <a href="https://leginfo.legislature.ca.gov/faces/codes_displayText.xhtml?lawCode=CCP&amp;division=&amp;title=1.&amp;part=1.&amp;chapter=5.5.&amp;article=3." rel="nofollow noreferrer">California law</a>, in a small claims action:</p>
<blockquote>
<p>The plaintiff may cause service of a copy of the claim and order to be made by substituted service as provided in subdivision (a) or (b) of Section 415.20 without the need to attempt personal service on the defendant.</p>
</blockquote>
<p><a href="https://leginfo.legislature.ca.gov/faces/codes_displayText.xhtml?lawCode=CCP&amp;division=&amp;title=5.&amp;part=2.&amp;chapter=4.&amp;article=3." rel="nofollow noreferrer">Section 415.20</a> (a) and (b) says:</p>
<blockquote>
<p>(a) In lieu of personal delivery of a copy of the summons and complaint to the person to be served as specified in Section 416.10, 416.20, 416.30, 416.40, or 416.50, a summons may be served by leaving a copy of the summons and complaint during usual office hours in his or her office or, if no physical address is known, at his or her usual mailing address, other than a United States Postal Service post office box, with the person who is apparently in charge thereof, and by thereafter mailing a copy of the summons and complaint by first-class mail, postage prepaid to the person to be served at the place where a copy of the summons and complaint were left. When service is effected by leaving a copy of the summons and complaint at a mailing address, it shall be left with a person at least 18 years of age, who shall be informed of the contents thereof. Service of a summons in this manner is deemed complete on the 10th day after the mailing.</p>
<p>(b) If a copy of the summons and complaint cannot with reasonable diligence be personally delivered to the person to be served, as specified in Section 416.60, 416.70, 416.80, or 416.90, a summons may be served by leaving a copy of the summons and complaint at the person’s dwelling house, usual place of abode, usual place of business, or usual mailing address other than a United States Postal Service post office box, in the presence of a competent member of the household or a person apparently in charge of his or her office, place of business, or usual mailing address other than a United States Postal Service post office box, at least 18 years of age, who shall be informed of the contents thereof, and by thereafter mailing a copy of the summons and of the complaint by first-class mail, postage prepaid to the person to be served at the place where a copy of the summons and complaint were left. Service of a summons in this manner is deemed complete on the 10th day after the mailing.</p>
</blockquote>
<p>It's apparently true that you cannot ordinarily serve via publication in a small claims action in California. But, if you can find an adult living at his address or working at his workplace, you can do a substitute service under these rules.</p>

california civil-law