Peter vouches for the Master [Jesus] and doesn't know that He is not obligated to pay the temple tax, but since Peter has vouched for Jesus [in ignorance, allegedly] Jesus doesn't leave Peter to meet the financial obligation himself. What I like about Jesus is that he tells Peter that the money will be in what Peter does best: fishing. The ability to pay the tax was located within two things: the command of the Lord, and the gift that the Lord had already placed within Peter.  So, when the Lord has given me the command [by His Spirit and in His Word] He will unlock the opportunity for me to use the gifts He has invested in me to bring fish into the Kingdom. [And] When I use His gifts to bring fish into the Kingdom, the fish will take care of the taxes of the temple [utility bills, pastor's compensation, existential repairs, staff compensation, maintenance to the temple, etc.].