These days, with banks tightening up lending and credit, every little bit helps in establishing a good credit rating for your business.

Here are six ways to make sure your company’s rating stays high, especially for a small business, sole proprietorship or start-up:

1. Register for a tax identification number. If you are a sole proprietor, consider incorporating your business. This will legally separate your personal finances from those of your business so that you can build a separate credit history. Next, apply for a tax identification number from the IRS. You’ll use this to file your taxes as an incorporated business and to register your business with credit bureaus such as D&B.
2. Get a DUNS number. If you are starting a business, get a jump-start on building your credit history by applying online for a DUNS number at D&B’s small business iUpdate portal. This nine-digit code is used by D&B and other credit bureaus to identify your business and maintain a credit file against it. If you already have a business credit file with D&B, be sure to review it and correct any inaccurate information.
3. Apply for credit from suppliers. According to business credit specialist Marco Carbajo, the best place to start building credit as a start-up is with suppliers. You can do this by applying for lines of credit to finance purchases such as office supplies, computers, inventory and so on, with flexible payment terms of net 30 or 60 days. Carbajo advises that you choose suppliers whom you’ll likely deal with on a regular basis so that you can continue to build and maintain your credit (as long as you pay them on time).
4. Separate personal and business finances. Further separate your business and personal finances and start building a business credit score by opening a business bank account and putting expenses in your business name. You should also apply for a business credit card. Start by approaching your existing bank or credit card issuer – since you already have a relationship with them, approvals should be easier.
5. Pay your bills on time. Since your Paydex score is based on your bill-payment habits, never miss a payment date. If your cash flow can tolerate it, you might also consider paying your bills ahead of time to increase your Paydex score.
6. Monitor your score. According to D&B, the credit score of about one in three businesses declines over just a three-month period. So, plan on monitoring your credit once a quarter so that you are aware of what’s happening and how it might affect relationships with suppliers and lenders. It’s also a good habit to review your credit file to make sure it’s current and accurate. Any changes to your business — such as location, number of employees, outstanding suits/liens and revenue — can impact your credit rating.

For more on improving a credit score, go to the Small Business Administration website.