Significant details have emerged about Tuesday’s Budget. We know that, after seven years of austerity, this Budget is actually going to add cash to the economy, rather than take it out.

However we have not seen the full package and much remains unclear.

Here are the key things to watch.

1 – How do the numbers add up? The surge in economic growth makes completing the budget so much easier. Before they stand up, Ministers Noonan and Howlin have already met their budget target of cutting borrowing below 3 per cent of GDP, with something to spare. If they did nothing tomorrow, then borrowing next year would be targeted to come in at 2.4 per cent of GDP. Budget measures will increase this to about 2.7-2.8 per cent. This is a net addition of about €600 million to borrowing . But within this net figure there will be a lot of vital pluses and minuses.

2 – Who gains most? There isn't a lot of extra cash to spread around. So there will be a huge focus on the calculations showing what income groups will gain most from the tax package. We know there is likely to be a one-point cut in the top income tax rate, a widening of the standard band and USC changes. There will also, somewhat bizarrely, be some tax relief on water charges. But without all the numbers it is impossible to work out who the biggest gainers will be, either in cash terms or as a proportion of income.

3 – Any nasties for high earners? One thing to watch it whether there will be anything done to claw back some gains from higher earners. A higher USC charge on self-employed earners, charged on incomes over €100,000, was due to abolished. But will it be? The "fairness" argument will be a key one after the budget.

4. Are there hidden hits? Some tax increases have apparently been canned as the figures improved, as they are now not needed to meet borrowing targets. But there will be higher charges and taxes in some areas – apart altogether from the already announced water charges. The levy on private pensions will fall, but is likely to remain in place at a lower level. If health insurers have to pay out more due to health policy changes, then health insurance costs will rise.

5. Where does extra cash spending go? Minister Brendan Howlin can't exactly "splash the cash", but he has a few hundred million extra to spread around. Some of the highlights have emerged – 1,000 extra teachers, extra Gardaí, more money for health – but as with taxes, the full figures will tell the story. In particular, there will be a focus on whether some of the more painful cutbacks of the austerity years have been reversed.

6 – Where will money be invested? Government investment spending was slashed during the downturn. Now some rebuilding will start. A €200 million annual package for social housing is expected, but where else will state cash be invested ?

7 – What happens next? The budget will also include the publication of a three-year plan. This will outline tax and spending plans for the next three years, beyond the next election. A key issue here will be how specific this plan will be in terms of tax and spending measures in future, particularly for next October's budget, the last possible one before the general election.

This will potentially be another big source of post-budget debate.