Growing concerns about one or possibly two more interest rate rises come as a host of the major government benefit payments increase next month.

September ushers in the biannual uptick on pension, JobSeeker, Youth Allowance, rent assistance and parenting payments for 5.3 million Australians.

The twice-yearly increase looms as worse-than-expected inflation data released Wednesday ignites the possibility of another interest rate hike next month, but almost certainly guarantees a hike in November.

If that’s not frightening enough, the cost of stamps goes up 15 cents to $1.85 on September 1.

The benefit increases kick in September 20. From that day, the maximum pension rate for couples goes up $55.60 to $1866 a fortnight. The highest rate for singles goes up by $36.80 to $1237.70 a fortnight.

JobSeeker will go up $16.20 to $833.70 per fortnight for a single person without children.

Parenting payments increase by $20.90 to $1087.20 a fortnight for singles, and $14.80 to $763 per fortnight for partnered recipients.

Social Services Minister Tanya Plibersek says pensions are 25 per cent higher than when Labor was elected, and people on JobSeeker are getting $4700 more each year since the change of government.

The September indexation tallies an extra $4bn in payments, spread across 5.3 million people.

“Whether it’s paying the rent, putting food on the table or covering everyday bills, this extra support will help Australians on income support make ends meet,” Ms Plibersek said.

“We’ll continue to make sure the system is there to support those who need it most, ensuring that everyone can make ends meet and no one gets left behind.”

Though benefits payments are increasing, the way the government assess someone’s income is being tightened.

Deeming rates are the figures the government uses to assume a person is making money from their savings accounts, investments and loans, stocks, and payments from their superannuation or life insurance provider.

The rate of deemed income on assets goes up next month – from 1.25 per cent to 1.75 per cent on assets up to $66,800 for singles, and $110,600 for couples. Any asset over those thresholds, the tax office assumes earns 3.75 per cent each year, and this calculation affects a person’s social security entitlements.