KiwiSaver members over 18 have until the end of the week to ensure they have contributed enough to their accounts to get the Government's full $521 subsidy.
Savers have to put in $1043 for the year to June 30 to be eligible for the full amount, which has halved from previous years.
Up until this year, savers were matched by the Government for every dollar they invested up to the maximum $1043.
But the Government cut back the subsidy in the 2011 Budget, meaning savers get only 50c for every dollar they invest up the maximum.
Savers can check their balance with either the Inland Revenue or their provider to see how much they have contributed so far this year and then make a top-up if needed.
A spokesman for Inland Revenue said that as long as any lump sum payments were banked into the relevant account no later than the last business day before June 30 they would be included for the tax credit entitlement.
"Although we would suggest members don't leave it that late."
Inland Revenue figures for the year to June 30, 2011, show just 45 per cent of members or around 420,000 people received the full subsidy.
It is not available to people under 18 years of age and those who have not been in KiwiSaver for a full financial year to June 30 will have their subsidy pro-rated to reflect how long they have been a member.
Retirement Commissioner Diana Crossan said savers needed to ask themselves if they could afford to make the top-up.
She urged those who could afford it to make the most of the subsidy.
"This is an incentive that the Government has set up for people to use - so we would encourage people to use it," Crossan said.
Those who earn more than $52,000 yearly and have put in the minimum contribution rate of 2 per cent do not have to worry as they will have put in enough already.
Crossan said self-employed people were one of the groups most likely to miss out if they did not meet the minimum contribution rate.
She said people who were only putting in the minimum contribution to KiwiSaver also needed to consider that it might not get them where they want to be in retirement.
By Tamsyn Parker Email Tamsyn