Overstay on visa

this starts officially from the 1st of jan so no one will have had a problem yet.  however, expect the various countries in the European union to be looking more closely at the travel timings of anyone from the UK.  it is quite possible that your passport will be stamped on entry so that it is quite clear how long you will have been in the country should the police stop you to check. there is nothing to do with being a tourist or a worker because if you were a worker you would be on a visa or a resident.

I’m sure what you want to do would be against the law.

I think your questions would be addressed to HMC&E and or Border Control UK

It has always been illegal to stay more than 90 days in Spain if you are a visitor, not a resident. However until now Spain has turned a blind eye to this as the UK was in the EU. Now we have left all bets are off. After Transition ends UK nationals are regarded as less eligible and no allowances will be made. From 1 January all entries by passport will not only be logged (as they have been already in recent years) but you will not be allowed back into Spain in the future if you are found to have overstayed. Short of swimming the Channel you cannot evade their scrutiny, don't risk it! You can still come for two x three-month periods each year. Just no more than 90 days in any 180 day period.

Chris

As from 1/1/21, should you try that and be found to have overstayed you can be fined - heavily - and be barred from returning for up to 5 years.

As Chrisso points out passports will be logged and as British nationals can no longer use EU e-gate from next year, passports will be carefully checked