The move was necessitated due to "difficulties" faced by developers carrying out large-scale projects including SEZs and IT Parks, Housing and Urban Development Minister K Radhakrishnan said.
He moved a bill in the state Assembly to amend the Tamil Nadu Town and Country Planning Act, 1971 for this purpose.
The validity period of planning permission was fixed as three years in 1971 when large-scale development activities were not taking place in the state, he said.
"It has been brought to the notice of the government that difficulties are (being) experienced by persons carrying out large-scale development activities like Special Economic Zones, IT Parks, malls and townships in implementing them within the prescribed period of three years," he said.
The government has therefore decided to amend the Act, he added.