you may not owe the underestimated tax penalties for 2025 if your 2025 W-2 withholding is 100% of your 2024 tax or if your 2024 adjusted gross income was $150,000 or more than 2025 W-2 withholding would need to be 110% of your 2024 tax. With so much self-employment income you probably should sit down with a tax advisor. There may be ways to reduce some of the extra tax burden like contributing to a retirement plan. Possibly an S corporation. Also keep good records of the expenses you incur with the locums because most if not all would likely be tax deductible
