"I think they're in some challenging territory. We've got an agreement in place and we're happy that they're acting consistent with the agreement. We are not trying to second guess the decisions the governor should make.
"The flexibility is there to allow the governor to make balanced judgments about the economy and PTA accommodates that. We are happy to see that continue and review it next year."
The agreement automatically comes up for review at the end of governor Graeme Wheeler's five-year term in September 2017.
"By then there will be a bit of a clearer view about where inflation rates are," English said. "Anyone can see there's been some reasonably unusual circumstances ... like the huge drop in oil."
He added that lower ACC levies were probably also a factor.
"The economy is growing at a moderate, steady rate, better than most developed economies. The PTA doesn't seem to be creating significant problems for the economy."
English said he was reluctant to prejudge the outcome of the review, which would include advice from the Treasury, but noted he hadn't seen any compelling argument that the agreement itself could change or any particularly coherent alternative.
"In the long run, the agreement is there to assist in the anchoring of inflation expectations because people think stable, moderate inflation works for an economy, that's the point of it, and those objectives haven't changed."