Wealthy landlords have vowed to raise rents for struggling tenants after the Budget's sweeping changes to property taxes, even if the reforms don't affect them.

Treasurer Jim Chalmers announced the major reforms when he tabled the Federal Budget on Tuesday night, including winding back negative gearing and axing the 50 per cent capital gains tax discount on all assets held for more than 12 months.

The overhaul will restrict negative gearing and scrap the 50 per cent capital gains discount. 

Landlords could previously offset investment losses - such as a $1,000 monthly shortfall between rent and mortgage - against their taxable income. 

Under the new rules, investors who purchase established properties after May 12, 2026, will no longer be able to claim these deductions. Some may try to cover losses by increasing rents, potentially by $1,000 per month in this example.

Budget forecasts on Tuesday predicted the changes would add just $2 a week to the average household's rent, but AMP chief economist Shane Oliver told the Daily Mail that figure 'sounds like more of a guess'.

He said: 'I don't know how much work was put into that number, but the new investor will either need a lower property price or higher rent to participate in the rental market.' 

The changes only apply to established properties purchased after Budget night, but that hasn't stopped landlords - many of whom are unaffected by the changes - from flooding social media with threats to raise rents anyway.

Just hours after the Budget was tabled on Tuesday, a member of the Landlords Victoria Facebook page wrote: 'Landlords. Increase rents now. Rental freeze will be the next thing coming.'

The Greens previously called for a national rental freeze to ease the pressure on tenants, even though the Commonwealth doesn't have the power to freeze rents unilaterally. Labor rejected the Greens' campaign.

One X user, who already owns property and is exempt from the changes, wrote: 'As a landlord I will now increase my rent and I will tell my tenants why I had to do it. Don't think I will sell now. I will wait it out until there is a change of Government.'

Another user said: 'All my tenants will now receive rent rise notifications by end of week. I will not renew or extend current lease agreements. I pay more, you pay more.'

A third person said: 'I'm just trying to get rich from my tenants. It's working - I just put the rent up another $40 pw. Starting to make life money now.'

Someone else wrote: 'As a landlord of multiple residential, commercial and rural properties I'll be jacking up rents and calling it the Albanese rental surcharge tax.'

The comments echo landlord Jack Henderson, 29, who owns 17 properties worth $60million and told the Daily Mail this week: 'I'm not a charity.'

He said renters would be treated 'very poorly' under the Budget changes.

'They got a one per cent tax cut on $28,000 worth of income and they will likely get a 10 to 15 per cent increase in rental prices,' he said.

Tenants rubbished the government's forecast, pointing out weekly rental increases normally occur regardless of policy changes, and usually in multiples of $10. 

'Hands up anyone who has had a $2 rent rise since the 80s/90s,' one renter posted on social media. 'Clueless politicians, making policy for stuff you know nothing about.'

Another added: 'Just keeping a rental roof over one's head is a major achievement.

'Our government expects a $2 a week rent increase - must be on the same delulu juice that Trump mob is on.' 

Housing activist Jordan van den Lamb - known online as PurplePingers - added: 'To be perfectly candid, I feel like when Treasury did the modelling for rent rises I don't think they accurately accounted for the landlord derangement variable.' 

AMP chief economist Shane Oliver said it was difficult to forecast an exact dollar figure, but said the $2 prediction 'sounds like it's on the low side'.

He said changes to capital gains tax will cut into profits upon selling, and negative gearing changes have removed the ability to deduct losses for investors who buy established properties after Budget night.

Under the previous capital gains rules, investors only had to pay tax on 50 per cent of their capital gain when selling an asset. The cost base will now be indexed to inflation before the gain is calculated, resulting in a likely higher tax bill. 

The combined effect of changes to the capital gains discount and negative gearing rules will likely result in landlords hiking rents to compensate for both tax changes.

Mr Oliver said: 'You're getting less capital growth because of the capital gains tax and you're no longer able to deduct losses on property, so your net rental yield is lower.

'To compensate, investors would require higher rental yields, and it's hard to put a number on it, but it would be more than $2 ... when the average rent is $800 per week, $2 is a trivial portion of the rent being charged.'

He said there was no logical reason for investors who are exempt from the negative gearing changes to hike rents in the short term, but that prices could rise anyway due to low vacancy rates.

Vacancy rates in capital cities are currently very low, and the government predicted in Budget documents that the tax reforms would reduce the rental market by a further 35,000 dwellings.

'Landlords have the pricing power and the government has almost given them an excuse to put up rents because vacancy rates are so low,' Mr Oliver said.

New builds are exempt from the property tax changes, which the government says is an effort to expand the housing supply.

But Mr Oliver said investors are likely to leave the residential market altogether, opting instead for commercial property - which is also exempt from the changes - or shares with franked dividends.