There are two common business letter formats, the popular one is the block format, which is easier to use and there is no indentation. Another format is the indented format, which required some indentation. Make sure to use the correct template when writing your formal business letter and make sure everything is in the proper layout. The margin on all sides should be 1-inch, for more details, view the samples below.

Block Letter Format:

Indented Letter Format:

The two formats above are great examples of what a business letter should look like. You can either use the block layout as your sample or use the indented layout if you want to change the overall look.  There are many business letter samples and examples, browse through the site to find the example that is relate to your business letter.