Quick quiz for you.

Question One: How do you feel about paying more tax to fund public services? A) Supportive or B) Not supportive.

Question Two: What is your tax residency status? A) Scottish or B) Rest of the UK?

Question Three (one we’re all familiar with): Do you think Scotland should be independent? A) Yes or B) No.

I’m asking these three questions now because they’ve been interacting in quite an interesting way lately. The question about tax residency, for example, will have come up if you’ve been filling in a tax return. The issue of paying more taxes has also been raised by the recent National Audit Office report showing that, because of changes introduced by the Scottish Government, Scots paid almost £750m more in income tax in 2018/19 than the year before.

The reaction of Scottish voters to the Audit Office report has been particularly interesting. One Herald reader, who works 25 hours a week on minimum wage, asked what the extra £750m had been spent on. “It is utterly non-existent in my life and the lives of other hard-working, responsible and diligent Scots,” he said. But others were much more positive and said they were happy to pay a bit more tax for progressive policies.

READ MORE: Scots estimated to have paid £750m more in income tax following SNP tax changes

It would seem, from what I’ve seen, that voters in the second group who say they’re happy to pay extra tax outnumber those who are unhappy, and this is curious for two reasons. First, it appears to defy one of the basic rules of British politics, but it also obeys another rule of Scottish politics that runs much deeper.

The basic rule of British politics says this: do not raise taxes because voters won’t like it. More specifically, the rule suggests voters will say they don’t mind paying more tax for better services but vote for parties that lower taxes. It’s the difference between the publicity of opinion and the secrecy of the ballot - when things are secret, people can do what they believe, not what they think they should believe.

The thing is, though, political rules aren’t quite as simple as that. On the face of it, the rule works: Margaret Thatcher’s governments, for example, reduced income tax and won three elections, and Tony Blair’s governments did pretty much the same: they cut income tax further and kept on winning.

However, the details reveal something a bit more subtle. For a start, the Tories aren’t as tax-cutting as they say they are – the Thatcher governments cut income tax but also dramatically raised VAT. Isolating tax as an issue also fails to understand what truly motivates voters. There will be some who think excessively cutting tax will make public services worse and vote accordingly, but more important is how voters prioritise issues in their heads.

It works like this: tax rates, corruption, inefficiency, immorality – all of these matter to voters but none of them matter as much as the issue that, deep down, they really care about. It explains why Boris Johnson does well despite all the questions over his record (because some voters care more about Brexit). And it explains why the SNP continue to do well despite all the questions over theirs (because some voters care more about independence).

What this means in Scotland is the SNP can appear to break the tax rule and still do well because some voters care more about independence than taxes. It also means that the risk of higher costs or economic damage has no effect on some voters – witness the reaction of some to the economic risks of independence. They. Don’t. Care.

The SNP’s defence to all of this is that the greater tax burden is “progressive” and raises extra revenue for “first-class public services” but both claims are dodgy. First, Scotland’s public services are not first class, but the extra taxes also cannot be progressive when they apply to people earning £26,000. Wouldn’t it be more progressive to end benefits that can be claimed by the well-off? And what about council tax – was it progressive to freeze it, thereby benefitting affluent households more than poorer ones while also forcing councils to cut services?

The point is that, even though the Don’t-Raise-Tax rule is still relevant, here in Scotland the deeper magic of independence matters more; it also means public services can get worse and taxes can get higher and the SNP continues to do well. Maybe the new rule for politicians in Scotland should be: think about independence first. But maybe there’s another lesson too: often it’s the politicians who break the rules that do best in the end.