By the end of 2015 it expects to reach 95 per cent by volume.
The increased provisions have no implications for Tower's solvency as it had about $110 million of capital above the current solvency minimum required by the Reserve Bank as at March 31.
The company said it will continue with its capital management programme, under which it expects to return $34 million via a buyback of shares.
"The resolution of Canterbury claims remains a key operational priority for Tower, with a dedicated team committed to providing certainty for customers and shareholders as they work through outstanding claims," the company said.
It will release the final figure for its claims provision and associated impact on earnings with its first-half results.
Underlying earnings in the first half were $17 million to $18 million, which would be as much as 37 per cent up on last year's net profit of $13.1 million.
"The anticipated improved earnings result has been supported by premium rate increases, growth in Pacific earnings and investment earnings, in a benign claims environment," chief executive David Hancock said.
Tower's shares resumed trading after the announcement, having been halted on Wednesday pending the release.
The stock dropped 2 per cent to $2.16, having surged 32 per cent in the past 12 months.
The stock is rated a 'buy' based on the consensus of four analysts polled by Reuters.
See Tower's latest announcement here: