That's the first step. After that, you end up in an infinite redirection loop.

HTTP/1.1 302 Found
...
Location: http://www.sanmateocountytaxcollector.org/SMCWPS/pages/secur
+eSearch.jsp
...
Client-Response-Num: 9
Client-Warning: Redirect loop detected (max_redirect = 7)
...
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It's probably cause it's trying to set cookies and they're not being handled.

Set-Cookie: JSESSIONID=0000WK9hTtPjeyIqUyVwqxfrxIQ:-1;Path=/
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If so, giving LWP::UserAgent a cookie jar will do the trick. Using WWW::Mechanize would also do the trick.