To widen your basement stairwell and door frame, you’ll want to get a professional estimate since this involves structural changes. The cost can vary significantly depending on your location, but you might expect to pay between $500 to $1,500 for the drywall removal and framing adjustments.
First, you should check if the wall is load-bearing. If it is, you'll need a licensed contractor or structural engineer to assess the situation and possibly install a support beam. This could increase costs, as structural work typically ranges from $1,000 to $3,000 depending on the complexity.
For the door frame, if it requires resizing, you’ll also need to factor in the cost of new framing, drywall, and finishing work, which can add another $200 to $600 to your project.
I recommend getting 2–3 local quotes from licensed contractors on Handyman.com to ensure you're getting a fair price and quality work. They can provide you with detailed estimates based on your specific needs and local regulations.
— Assisted answer