Ryan Bridge: Labour and National making it obvious they're fighting for the centre vote

Labour has finally seen the light on interest deductibility.

That's where a landlord, like any other legitimate business in New Zealand, is able to deduct the expense of its capital borrowing, i.e. a mortgage, against taxable income.

After expenses, what's left over is taxed.

This is a genuine surprise to me. The word I'd been getting from some Labour MPs, and the industry, was that they would allow a 50% deduction rather than the current 100%.

Of course, the deduction has always made sense and arguments against made little.

'Housing shouldn't be a business' because it's essential. Always been a bogus line. Food, electricity and water are also essential. They're all free and able to deduct interest on their borrowing to own and build supermarkets, wind turbines and treatment plants; whether publicly or privately owned.

Two reasons for this.

Was eloquently explained by Deloitte partner Robyn Walker on this show a few minutes ago. Labour's capital gains tax revenue would have been hit by landlords claiming the deductions at point of sale, leaving a hole in their free GP budget.

It's also a play for the centre. They're dropping in the polls. The nine new taxes adverts are, I think, largely to blame.

Continuing landlord tax cuts (as they like to call them) is a play from the same political handbag as National's supermarket break-up.

Neither party's MPs like the move. They're Captain's calls. They're centre plays. But they don't, in the hearts, these MPs, backing them.

On latest polling the legacy parties are scrapping for less than 60% of the vote, their lowest collective share on record.

National's trying to out-Labour Labour, and Labour's trying to out National National.

The risk for both is it that it only angers their base who run screaming into the arms of Chloe or David.