Can I still use my limited company if I'm inside IR35?

Yes, you can still operate through your limited company while inside IR35, tax and National Insurance are simply deducted at source on that engagement's income before it reaches the company, similar to a payslip. Many contractors run a mix of inside and outside contracts through the same company, or use an umbrella company for inside IR35 work instead. Whether it's still worth maintaining your limited company depends on your overall mix of work and costs, so it's worth reviewing with an accountant if most of your contracts turn out to be inside IR35.