Key Points on Work-Related Deductions

Ordinary and Necessary: The IRS allows deductions for expenses that are both ordinary (common and accepted in your trade or business) and necessary (helpful and appropriate for your work).
Work-Only Use: Items must be used exclusively for work to qualify. If you use the rain gear for personal purposes, it may not be fully deductible.

Since the description of “rain gear” is vague:

Your Choice of Item: You have flexibility in choosing what to purchase, as long as the item is reasonable and suitable for the class/job. A $200 rain jacket might be deductible if it's a high-quality, durable item commonly used by firefighters.
Reasonableness: The IRS may scrutinize overly expensive purchases. If most firefighters would consider a $50 jacket sufficient, a $200 jacket might raise questions. However, if the more expensive option is specifically required for safety or functionality (e.g., fire-resistant or heavy-duty gear), that could justify the cost.

Keep Receipts: Save receipts for the rain gear and any other items you purchase.
Explain Your Choice: If your item is more expensive than a basic option, document why you chose it (e.g., superior quality, better durability, safety features).
Class Requirements: Keep a copy of the class's recommended item list as evidence that these purchases were necessary for the course.

Reimbursement by Employer: If there's any chance your employer might cover some or all of the cost with proper justification, ask first. Reimbursed expenses aren’t deductible.
Out-of-Pocket Deduction Rules: If you’re itemizing deductions, unreimbursed work expenses like this are generally deductible only if they exceed 2% of your adjusted gross income (AGI). However, this rule does not apply to 2018–2025 for employees, except for self-employed individuals.

If you're unsure, consider:

Consulting with HR: They might provide guidance on what others typically purchase for the class.
Professional Tax Advice: If the deduction could be significant, consulting a tax professional would help ensure compliance with IRS rules.

In short, you have discretion in choosing the item, but staying reasonable and documenting your choice will help justify the deduction if questioned.