All right, not on an empty stomach then.

How about making your tax cut get bigger over time, for example? Not by tweaking some previously unnoticed work deduction - the Tax Office will notice it before you do, anyway - but by investing or paying off more of the mortgage. Or even sticking more into super.

At the risk of getting personal, the best way to go depends on how old you are, and how much you earn. At 60 and on an income that puts you in the higher tax brackets it's a no-brainer. Put it into super, because the contribution tax is only 15 per cent, and it's free when you take it out.

Between 55 and 60, super also comes out ahead of repaying the mortgage, but it's not necessarily better than gearing into a property or the sharemarket.

Converting the mortgage into interest-only and using the savings to pile more into super is one strategy.

When you take your super out tax-free at 60, then pay off the mortgage.

Below 55 the rule of thumb is that the lower your tax rate, and the higher interest rates are, the better paying off the mortgage looks.

It seems strange that paying off the mortgage works better on lower than higher incomes, but it's because you have more after-tax dollars to play with, making super less competitive.

The big advantage of super is that 85 cents of every dollar going in is put to work, compared with paying off the mortgage, or gearing, where only 58.5 cents on the top marginal rate of every dollar you earn is invested.

On higher incomes this gives super a head start. Macquarie Advisory Service's executive director, David Shirlow, has calculated the trade-off between borrowing costs and investment returns, to work out when to pay off the loan, salary sacrifice into super or negatively gear.

Only on the 31.5 per cent and below tax rates is paying off the mortgage the best strategy, and even then that's if investments over 10 years return exactly zero.

As soon as you get a return of 1 per cent, super kicks in. But you cross the threshold on a 5 per cent a year return, 5 per cent interest rate, when gearing is better.

From then, as long as the return stays the same as the interest rate, gearing is best.

On a tax rate of 41.5 per cent, which starts on an income of $80,000, super kicks in earlier. Paying off the mortgage is better only when interest rates are above 7 per cent, and investment returns are below 5 per cent.

Otherwise super is best, until you get up to 7 per cent returns, and interest rates below 10 per cent when gearing takes over.

On the top rate of 46.5 per cent, which doesn't kick in this financial year until $180,000, paying off the mortgage is better until investment returns exceed 1 per cent. And you'd have to be an extreme pessimist to think returns won't exceed an average 1 per cent a year.

Not surprisingly, on the top marginal rate super is better until returns hit an annual 7 per cent, in which case gearing looks more attractive.

Shirlow's figures are for the sharemarket which, it turns out, fares better with gearing than property.

"With real estate you get all your capital in one lump; that makes gearing a bit worse because you're pushed up into the top bracket."

A study by Zurich Financial Services shows that on an investment returning 3 per cent income and 6 per cent capital growth, gearing beats super on the 31.5 per cent marginal tax rate, but super wins on the higher brackets.