Budget Countdown: On Wednesday Brian Cowen will find himself in charge of important levers for the housing market and the construction sector.

It is in the Government's gift to change mortgage interest relief on income tax, stamp duty or investor-friendly tax reliefs on property in ways that could affect the market.

The housing market and construction sector are hugely important to the economy, with the construction sector now employing 250,000 people and accounting for one-third of all the new jobs.

According to the latest exchequer returns, house buyers now pump over €2.6 billion in revenue into Government's coffers each year. If some reliefs are changed, for instance mortgage interest relief, could this picture change?

Mortgage interest relief isn't what it once was. In the rising market of the last decade, it merely worked to keep prices a bit higher than they otherwise would have been.

But the higher relief available to first-time buyers gives them a slight advantage in the market, a feature Mr Cowen is likely to retain in next year's Budget.

First-time buyers also gained from the decision last year to abolish stamp duty for first-time buyers for purchases up to €317,500, with reduced rates applying to purchases up to €635,000. In a rising market, stamp duty kept prices lower than they would have otherwise been and diverted money to the Government.

Since their inception, by allowing potential purchasers to divert the monies they would have spent on stamp duty, these changes have given potential buyers more resources with which to bid and this has helped continued price strength. Further changes to stamp duty are less likely this year, but if they happen a similar effect is in prospect.

But the elephant in the room remains property tax reliefs. A variety of these have incentivised the purchase of second dwellings for rental purpose by allowing buyers to offset the capital cost against rental income.

When announcing last year's budget, Mr Cowen announced a review of these allowances.

In a recent review of the market, the AIB cautioned against any change to property tax reliefs that might "destabilise" the market.

If they are abolished, many investors will leave the market, lowering demand, possibly causing a temporary downturn in the prices of some apartments. If it has to happen, it might as well happen when the market is still strong. Still, it won't be an easy decision.