Islanders rallied in Market Square to hear from the deputies who are against GST.
Co-organiser Dominic Naermont told Island FM ahead of the protest that he expected around 500 people to turn out.
While it is difficult to gauge exact numbers, Market Square was packed with protestors, placards and megaphones.
Dominic Naermont says deputies opposed to GST spoke about their opposition to the plan and their ideas to raise revenue without GST:
"All the speeches were really motivational, and it's clear to see people are behind the rally.
"The deputies that did speak genuinely care about everyday islanders, which is really nice to see."
He spoke to many who attended and said some of the stories were upsetting:
"It was about how it's going to affect their families.
"The younger people say they don't want to leave their island, and the older people were saying they don't want their kids to leave."
P&R's policy letter faces significant opposition with more than 20 amendments laid.
The senior committee say GST at 3% - plus government savings and a benefits package to cushion the less well off - is the fairest way to raise the revenue it estimates is needed to correct Guernsey's financial position.
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