Many membership programs have partnerships with car rental companies; they provide rental car discounts to their members as a membership reward or membership benefit.
If you are calling a car rental company directly, just ask if there are rental car discounts with that program or association. The agents will be able to access the correct discount code and quote you a rate.
If you are searching for car rental rates on the internet, you can get the specific discount number from the program that you belong to from that program's website for membership rewards. Often, you can then link directly to the rental company you prefer and the correct rental code will autofill in the proper place.
The company you work for may already have a discount affiliation with one or more car rental companies. Check with your Human Resources manager for information on possible car rental discount coupons and discount codes or with a reservation agent for the car rental company you choose.
Most rental agencies offer rental car discounts and programs for small businesses and those who are self employed, with discounts,coupons and specials. You can call direct to the car rental company to sign up. As well, most car rental websites will also offer a link for you to apply for a corporate or business account. In most cases, you will receive a car rental discount code that you can use immediately. Check here, for information on Business Car Rentals (Programs and Benefits)
If you are calling a reservation line and you are not a member of an association and don't have a coupon, ask the reservation agent if there are any "specials" that day, or a "special rate" they can give you. Most companies empower their agents to discount a rate (they often have discount codes they can use).. but only if you ask!