"This creates fairness concerns for those who have to file and have tax to pay.
"Significant numbers of individuals are now either required to file returns or are choosing to do so.
"It is therefore timely to consider whether it is still desirable to keep as many individuals as possible from actively interacting with the tax system."
If digital technology could deliver an annual tax return that already contained the information received from employers, banks and other income sources for a taxpayer to check, compliance costs could be kept low while avoiding the potential for some taxpayers not to realise they should be filing tax returns.
"The only action required for the vast majority of customers would be to check and confirm their details.
"Where applicable, certain individuals would also need to report other income received - such as overseas income where there was no deduction of tax at source."
International initiatives on the exchange of income information may also provide opportunities to provide overseas income details in the individual's tax statement.
PwC tax and private business leader Geof Nightingale described the proposed changes as fundamental and ambitious.
"The direction of travel is a positive one.
"The tax system touches nearly every New Zealander and redesigning the tax system is a huge challenge.
"It is crucial any changes are well considered and implemented as seamlessly as possible.
"Small businesses in particular would feel compliance costs in coping with the changes falling on them disproportionately in the shorter term.
"However, New Zealand businesses will be better off in the longer term, with the changes set to save them costs and time," Nightingale said.
KPMG's national managing partner for tax Paul Dunne said he welcomed the release of the green paper.
Businesses played a significant role in the tax system - not only paying significant amounts of tax, but also collecting tax for the Government from employees, investors and consumers.
"The changes will put much more focus on how business does this.
"It will also increase the demand for business to provide Inland Revenue with real time information."
"It is often easy for business to ignore tax proposals until there are concrete changes to the law," Dunne said.
"With this latest discussion document, businesses need to sit up and take note now.
"Once the future direction is set, it will be too late to complain that desirable and achievable benefits for business have not been met."
The green paper also proposes major changes to the way provisional tax might be paid and to the calculation of withholding taxes on investment income, which will become an increasingly important source of revenue and tax obligations as taxpayers in an ageing population rely increasingly on investments rather than wages and salaries.
Using withholding taxes as a way to collect unpaid tax is also proposed, as is the potential to simplify compliance with fringe benefit tax through more real-time provision of information by employers to the Inland Revenue Department, which might allow tax obligations arising from fringe benefits, employer superannuation contributions and employee share schemes to be incorporated in the PAYE system.
Withholding taxes might also be applied to a wider range of industries, given that the range of activities covered by had not been reviewed since 1957, when both the PAYE and withholding tax systems were first put in place.
Also in the frame for reform is the complex array of tax obligations created for beneficiaries and recipients of government assistance through such programmes as Working for Families.
On business taxation, the green paper says the current system of requiring businesses to pay provisional tax, based on an estimate of current profitability, "can present cash flow difficulties for businesses, in particular, because of the nature of the current rules for new businesses."
New businesses effectively face a double-whammy of provisional and final tax obligations in their first two years of operation, which do not recur once the firm has established its record as a taxpayer.
"The calculation and payment of business income tax could be done more 'on-account' as income is earned during the year - much like a PAYE system for businesses," the green paper says.
"One idea is by considering whether accounting profits with a few key adjustments, for example, reversing out capital gains and losses and excluding non-taxable income, could effectively be used as a better proxy for a business's end-of-year tax obligation.
"This has the potential to simplify the calculation of provisional tax and create more certainty for taxpayers and reflect cash flow."
Alternatives could include using a "a bespoke percentage of a business's turnover".
"Any review of the provisional tax rules would also have to consider changes to the standard uplift method of calculating provisional tax, together with the current safe harbour limits and use of money interest rules.
"A review of the tax pooling rules should also be undertaken to see if they can be improved and/or made available to more taxpayers," the green paper says.
On withholding taxes, the paper suggests that instead of reporting annually to their customers on tax obligations created by interest and dividends, banks and companies could provide the information straight to the IRD for inclusion in online documentation provided for taxpayers directly by the tax authority.
"Although there may be short-term costs for financial institutions and other businesses in order to provide this information, there are longer term benefits to those businesses and their customers - for example, more accurate and automatic withholding and increasing levels of compliance," the green paper says.
"There will also be long-term benefits to financial institutions as tax is integrated into business processes."
McClay said the government plans to deal with tax administration and PAYE/GST rules, and withholding taxes on labour income this year, followed by initiatives in 2016 on investment income information, individuals' interactions with the IRD, and business taxation.
Social policy interaction with the tax system would be tackled in 2017.
Public consultation documents will be released for each area of initiatives.
Read the full Green Paper here
