Kill the lawn now. That way you save unnecessary mowing. I would forget dethatching or aerating. Just spread seed. You can cut the dead grass short after this (or not). I would definitely look up Tenacity--I think it's use at seeding and several weeks later will give you great protection against weeds. Definitely make sure everything is dead before you seed. Two applications of roundup if need be but give the first application sufficient time to work and then maybe spot spray the second app.

What Mishmosh said. Although I would dethatch, but that's me.

@Joe: did you roll your soil after seeding to ensure good soil contact?

@daniel: no rolling, just back of the rake.

Joe, interesting. I thought making firm contact was a must. Good to know. I decided to give a reprieve to my lawn this year. It has been behaving and I've got too many other things to worry about without adding a lawn reno. Maybe next year.

I wonder if the OP is reading this thread...

Firm contact isn't necessary, the seed will do that. Grass seed is spiky for a reason; it works its own way into the soil, unlike some other seeds.

OP is reading, I got a like recently on my checklist, so this isn't an abandoned thread. He or she is just paying attention and hasn't seen fit to add anything at this time.

@mishmosh thanks. just got my tenacity. Previous homeowner neglected the lawn. Thatch is thick.

@morpheuspa Just incase we need to adjust the soil ph. Can we still put down lime or iron after seeding or this should only be done before seeding? Sorry i’m so new to this. (My husband applied spectracide lawn killer today)

If your soil test shows adjustments are needed, they should probably wait until spring. But post the test and we'll discuss it. Severe issues...well, we can start with something this fall, but it's going to have to be gentle on a new lawn.

Iron should be OK late in the season in smaller amounts, depending on what you use. I'm fine with Milorganite applications or light amounts of sprayed iron, but definitely don't stress the new grass when it's young!

@User Got it! thank you.

will post the the ph result once i got it.