not only would it but it will

[alpacinou]

Hello.

Are these sentences I have written correct and natural?

1. Imposing a green tax seems to be a great idea. Not only would it contribute to the cause of protecting the environment, but it would also promote economic growth.

2. Imposing a green tax seems to be a great idea. Not only would it contribute to the cause of protecting the environment, but it will also promote economic growth.

 

[Charlie Bernstein]

Hello.

Are these sentences I have written correct and natural?

1. Imposing a green tax seems to be a great idea. Not only would it contribute to the cause of protecting the environment, but it would also promote economic growth.

2. Imposing a green tax seems to be a great idea. Not only would it contribute to the cause of protecting the environment, but it will also promote economic growth.

For parallelism's sake, stick with either will or would throughout.

Would is better until the tax is done deal or highly likely to be.

 

[alpacinou]

For parallelism's sake, stick with either will or would throughout.

Would is better until the tax is done deal or highly likely to be.

Just so I'm clear, is this completely okay?

1. Imposing a green tax seems to be a great idea. Not only would it contribute to the cause of protecting the environment, but it would also promote economic growth.

 

[Charlie Bernstein]

Yes, indeed!

The but isn't needed, but it's fine to use it.