Holden and Lee
I think the advice you have been getting is wrong, or you have misunderstood.
As a non-resident, unless you have an income in Spain, you do not make Income Tax returns, but pay foreign owner’s property tax, and, if the property is valued at over 600,000 euros, patrimonio tax.
The bad news also is that in Spain it is your responsibility to pay taxes which you become liable for (IBI, as you call it council tax, rubbish collection tax etc). It is not the responsibility of the Town Hall etc. to tell you.
When you do pay late, interest is added and maybe fines too.