In reply to Robert Durran:
Weird that this is suddenly a story since rules on having sufficient funds seem to have been around for some time e.g. (from May)
https://www.guidetocanaryislands.com/minimum-100-euros-per-day-travel-spain...
Also note that the rules all say 'may' require (not must as in the headline), these rules have been in place for years for 3rd countries (which UK now is) , are people from US for example having there finances checked on a regular basis?
The details in the article are also incorrect in that it says 100 euro per day plus 900 euros , its actually 100 per day with a minimum of 900 euro (i.e. 9 days worth). In the ,probably unlikely, event that you did need to prove funds it appears a credit card with sufficient balance available is acceptable.
Also your thread title is obviously a bit disingenuous since this requirement has no impact on the actual amount that you might spend in Spain - I guess the only people who might risk being impacted are those looking to stay for close to the 90 day maximum who would theoretically need a fairly large balance available.