Polling of NRLA members conducted by Pegasus Insight found that 78% of landlords believe the legislation will make them more selective about who they rent to.
The NRLA said groups likely to be most affected include tenants with irregular incomes, international students without a UK credit history or guarantor, and renters impacted by the ongoing freeze in housing benefit rates.
The trade body said restrictions on rent in advance payments contained within the legislation could make it harder for tenants with limited credit histories to demonstrate affordability.
It also warned that the move towards open ended tenancies may reduce access to guarantors, given concerns around guaranteeing rent obligations without a fixed tenancy end date.
Separately, 90% of landlords surveyed said they were concerned about court delays when seeking possession of properties in legitimate cases such as serious rent arrears or anti social behaviour.
According to the NRLA, possession cases currently take an average of almost eight months to process and enforce through the courts.
The organisation also referenced comments from Law Society president Mark Evans, who has warned that the legal system requires further investment to prevent delays affecting both landlords and tenants.
Ben Beadle, chief executive at the NRLA, said: “Today’s findings paint a worrying picture for many renters and serve as an important reminder that reforming the private rented sector comes with considerable risk.
“Responsible landlords need confidence that tenants can sustain a tenancy. If the system makes it harder for them to seek those assurances, the result will be fewer options for those on the financial margins.
“Likewise, the Government’s failure to publish a clear plan to ensure the courts process legitimate possession cases far quicker than at present is causing considerable concern in the sector.
“Without this, the Government risks undermining landlord confidence at the very moment renters need more homes, not fewer.”
