Short answer: Yes, you should protest to the Appraisal Review Board even if you won a property tax reduction last year.  The appraisal district and the ARB consider each year de novo.  (That’s a legal term for “from scratch”.)  What happened last year is irrelevant to the appraisal district and to the ARB.  As they say in the NBA, “That was then. This is now.”

Incidentally, the flip side of de novo is that a substantial increase last year that went unprotested is irrelevant to your property tax protest this year.  The ARB won’t look with any more favor on this year’s protest just because you failed to file a protest against last year’s big increase.  See Why You Should Protest to the Appraisal Review Board Each Year – Regardless

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