There are two famous political maxims, which are almost always proven to be true:

1. All politics is local.

2. There are only two certainties in life: death and taxes.

One of the few things which unite these two statements is the Local Property Tax, which was passed by the Oireachtas in December 2012 and signed into law on St Stephen's Day that year.

A permanent legacy of the Troika era, the Local Property Tax was designed such that local authorities could choose to raise or lower it by 15 per cent if they so chose.

This naturally became something of a plank of the local elections - with (predictably) all the major parties pledging to refuse any plans to raise the tax, and to cut it wherever possible.

But the staggering thing about the local property tax is that now, 19 months after the Oireachtas chose to introduce it, it would appear the government has never really decided what it's supposed to do.

It's worth repeating. A full year and a half - and a bruising election - after the tax was passed into law, Fine Gael and Labour appear to be more at odds than ever about exactly how the tax should work.

Fine Gael's school of thought has been to use the tax as an accountancy exercise: if the extra tax is (mostly) going towards local councils, then the central government can cut its own funding accordingly.

As a result, the councils don't lose out (at least, unless they actively choose to cut their tax) but the central government's accounts become healthier: with no loss of services, the government can reduce its overall spending and inch ever closer to meeting its EU deficit targets.

(A similar outcome can be observed for Irish Water, where the central government has outsourced its water operations so that the spending doesn't show up on its central accounts.)

But Labour has a far different understanding of the tax - instead considering it as a new tax to fund new services. In their mind, a council should be free to increase its tax if it wants to run an extra local service.

So - if a council wants to build another recycling centre, or a controversial enormous library, it can therefore ask the locals to stump up that little bit extra for the privilege.

One would think that the two parties could at least have had some discussion about this in the 20 months between taking office and legislating for the property tax, But, seemingly not.

One would even think that the dispute would have been broached in the 17 months between the tax being introduced, and the subsequent local elections where several parties ran specifically on property tax platforms.

But, apparently not: the coalition has sleepwalked into a situation where, years after legislating for a tax, there's no agreement on exactly how it's meant to work.

Or did it?

Two weeks ago, on his last full day as Tánaiste, Eamon Gilmore accused Fine Gael of a "fundamental breach" of the property tax agreement by looking to cut the central funding to Dublin councils as part of the deal.

I was in Berlin with Enda Kenny - and at a doorstep, duly asked him about the issue. He claimed not to be aware of his Tánaiste's comments; fair enough.

But, I put it to him, isn't it absurd that 18 months after legislating for the property tax, there was no understanding of how it was meant to work? Many councillors had been elected on the understanding that the LPT was meant to act as new money for new services.

"Clearly a lot of councillors had very different understandings about the property tax. I think we made it clear on the principle of motor tax for quite some time," he replied.

"The principles here - let me repeat again - are that no council will be worse off starting here; that 80% [of the tax] will be retained within the council areas; and we still have to work out the details of how you actually implement that."

A day later Joan Burton was elected as the new Labour leader, and appointed as Tánaiste. I asked her how much of an issue the LPT was for Labour.

While the new Tánaiste explained that she hadn't yet discussed the issue with the Taoiseach - and fair enough - she added:

"What is important is that the promises in relation to property tax - that people would visibly see the spend of their property taxes going into their local area, and services..." the sentence was left unfinished.

"I also want to see, particularly in the greater Dublin area and in some of the other large urban areas, where there is a severe shortage of housing for families with children, that that would also see that kind of emphasis of investment in that area."

The answer thereafter migrated to a treatise on social housing - the suggestion being that councils should be able to use the property tax to fund their aggressive new campaigns to get back into the building game.

In some senses it's mind-boggling that the Local Property tax made it through the Oireachtas without some opposition TD or Senator managing to spot the gap between the parties.

But likewise it's also a sign of extraordinary laxness on the part of the government that it hasn't yet made up its own mind about how a fundamental 'reform' of the tax system - and an apparent 'empowerment' of the newly-rationalised local politicians - is supposed to take effect.

Joan Burton will be keen to ensure the government doesn't lose its sense of purpose in the post-Troika era - but anything other than a conclusive agreement on LPT will spell problems for the government, and specifically for Labour, in the years and elections ahead.

Gavan Reilly is Today FM's political correspondent. twitter.com/gavreilly