Can Twitter handle serious policy debates? This week has been dominated by tax policy - in terms of National's tax cut plan and Labour's proposed capital gains tax (CGT) - providing a challenge to Twitter's inherent requirement for brevity.

There was the usual lighter take on a weighty topic, but even humorous tweets could make serious points. This from @AliRomanos: "Income Tax Act is 3,852 pages ... 30 pages for CGT? Woah big shock. More spin by National." And Labour MP @chrishipkins ridiculed National's proposed tax cut with: "All those txting into tonight's leaders debate have probably just spent more than that tax cut John Key has promised them."

At the rawer parody end of the spectrum, @dirtydeedsnz - which claims to be run by a public servant - asked: "Wat if u in prison & u lease ur bunk to another inmate & u sleep on floor, but then u r moved 2 solitary confinement. R the proceeds CGT'd?" And @petrajane was one of many to seize on tax-cheese comparisons: "I really hope the international media is watching the NZ political race and makes the assumption our national currency is blocks of cheese."

Amid all this were genuinely insightful debates on policy details. Former Employers and Manufacturers Association president Alasdair Thompson (@ajthompson13) used Twitter to debate the merits of CGT with former Labour candidate @jordantcarter. Thompson: "All I can say is, you need to study it. Once people's homes are excluded the revenue to implementation/admin cost is awful."


Twitter was used to clarify the Greens' application of CGT, with @GraemeEdgeler asking @RusselNorman, "are you proposing to remove the intent requirement if we have a CGT?" Four minutes later, Norman responded: "Regular CGT in rest of OECD is based on objective test, ie capital gains, not subjective test, ie what was your intent."

On National's tax plan, Labour spin-doctor @ClintVSmith was doing the sums: "Key now saying tax cuts up to $1500pa per family. Maths says no. $1b/3.6m taxpayers = $275 pa each, $5.30pw. Unless, many get nothing ..."

David Cunliffe's own calculations on Wednesday's TV3 debate came in for criticism. This from RadioLive political editor Jessica Williams (@mizjwilliams): "Oh dear. Cunliffe's challenge to the PM on the cost of tax cuts got the figure wrong. Not $3.4b, $2.4b. Facepalm."

Useful comments on economic policies include New Zealand Initiative economist Eric Crampton (@EricCrampton), tax accountant Geof Nightingale (@Geoftax), economics blogger @TVHE, and Deloitte NZ Tax (@DeloitteNZTax).

Otago University political experts Dr Bryce Edwards (@bryce_edwards) and Geoffrey Miller (@GeoffMillerNZ) are following the impact of Twitter on the election campaign.