First of all, check whether Bitcoin is classified as a currency in your country or not. In 99% of the cases, it will be classified as an "asset" by the government. In such cases, the bitcoins that you receive from signature campaigns are not taxable (as long as these coins remain in your wallet).
It doesn't matter how much you cash out, you're being paid in something with value and that's the place you're taxed.
I second gentlemand's reply to the
other post, and this also applies to Wayan_Pedjeng's post
taxation happens at the time you receive something
(in any forms) regarded as income or addition to your wealth
if payment is in the form of bitcoin as an asset, the value of bitcoin at the time of transaction will be used for taxation