HOLYROOD’S tax-raising powers have come a long way in a short space of time.

The introduction of new taxes and reforms to existing ones – most notably Income Tax – have been the hallmark of recent Scottish Budgets.

But if reforms of this magnitude are unlikely to be on show tomorrow, then what should we be looking out for?

The highest profile among these recent changes – the introduction of five rates and bands of income tax – appears here to stay.

These may give Derek Mackay the room for manoeuvre needed to manage, in his own words, the “tolerable levels of divergence” needed to support investment in public services.

He may opt to change the existing rates of income tax (currently 19, 20, 21, 41 and 46%), although this could be fraught with political difficulties.

Alternatively, he could retain the same headline rates, but extend or restrict the size of each tax band.

This potentially buys him the political cover necessary for the Budget’s survival. He could opt to give lower earners more of their money by increasing the scope of the starter rate in a trade-off for lowering or limiting the level at which people start paying the higher and top rates.

Such moves would inevitably fuel the perception that Scotland is taking a different tax tack to the rest of the UK. It will also give air to the debate on the impact of tax competition on the performance of the wider Scottish economy.

The Finance Secretary may also find himself under pressure to conform to other changes in the UK’s October Budget. The first-time buyer’s relief for owners of shared tenure homes and the proposed 1% levy on non-resident buyers are likely to have passed through his in-tray.

In spite of these significant changes, there remains the sober realisation that the Scottish public is, by and large, oblivious to the scale of change at hand.

Four-fifths of people recently polled by the Chartered Institute of Taxation said that they needed better information over how taxes are decided in Scotland.

Mr Mackay should use the Budget to commit to the introduction of a Scottish Finance Bill - first hinted at in September’s Programme for Government - to help identify, scrutinise and amend tax legislation.

He will find little resistance from those of us determined to see a stronger light shone on the devolved taxes.

Moira Kelly is chair of the Chartered Institute of Taxation’s Scottish Technical Committee.