It's getting easier to buy a home these days. Mortgage rates remain low, and many lenders offer mortgages with as little as a 5 percent down if you have good credit.

Lenders are typically protected from loss on mortgage loans by one of the government insurance programs, such as Fannie Mae or Freddie Mac, or they require those with down payments of less than 20 percent to purchase private mortgage insurance to protect the lender against loss if the homeowner defaults. Private mortgage insurance makes it possible for many people to get a mortgage. But PMI can be costly and tricky.

Here are five things you should know:

The cost of PMI depends on your credit, the amount of your down payment and the length of the loan

For example, if you put less than 10 percent down on a 30-year loan and have excellent credit, your monthly PMI will be 0.41 percent of the loan — roughly $35 per month per $100,000 borrowed. A higher down payment of 15 percent could cut your monthly cost to $15 per month per $100,000 borrowed. Credit scores matter a lot. With a 780 score, your PMI is 0.41 percent, and with a score of 700, the PMI percentage increases to 0.87 percent.

If you're a veteran, you don't pay PMI

Veterans avoid PMI through the VA loan program. If you're a veteran you can get a loan with zero down payment.

PMI is not required after you have 22 percent equity in your home

Eventually, you will build equity in your home by making regular mortgage payments. Or the value of your home could rise, and a reappraisal after one year may determine that you have reached 22 percent equity. PMI is supposed to drop off your monthly bill automatically when your equity reaches 22 percent. But you should keep track of the equity in your home, and you might even want to refinance when your equity rises to 20 percent.

Even FHA mortgages require insurance premiums, and this insurance may never go away

FHA loans carry federal mortgage insurance (known as MI), which is essentially the same thing as PMI. But on a 30-year fixed FHA loan, MI never drops off and it carries a higher rate of 0.85 percent for buyers making a 5 percent down payment or less. But you can always refinance the loan as your equity grows. And an FHA loan may be your only option.

There are several ways to pay PMI

Usually, PMI is included in your monthly mortgage payment. But some lenders will wrap the monthly payment into a slightly higher interest rate on your mortgage. Because mortgage interest is deductible, this gives you a bit of an advantage. And some lenders will give you a discount if you pay the entire PMI up front in a lump sum. It's an enticement but wasted money if you sell the home before reaching equity of 22 percent.

My mortgage expert, Daniel Chookaszian of Perl Mortgage, reminds me of one other advantage of putting less money down and paying PMI. He notes that you can keep the cash that doesn't go into your down payment for emergencies.

But I hope your goal is to build equity and escape PMI payments. That gives you security. And that's the Savage Truth.

Terry Savage is a registered investment adviser. She responds to questions on her blog at TerrySavage.com.