Under the US law it is must to have a blog disclosure policy published on your blog page. A violation of these rules can land you in trouble with the Federal Trade Commission of the country and you might be charged a fine of an amount up to $11,000.
Blog disclosure policy can be based on a couple of written paragraph or a full-page document that should be published clearly on your blog. This is a must for all types of blogs in the US and other countries. The law is more effective on the blog's hosts who are based in the US.
You should create a list on a page explaining the details of your written work. For example, you can say you occasionally write paid blog posts. This requirement is very essential if you are a paid blog writer by a commercial firm, which has been pursuing and implementing an agenda using you as a tool. There is nothing wrong in it, but do not hide it.
You will also need to mention other types of benefits you might be receiving from a firm or person as compensation for writing blog posts for them. These are other than cash payments. For example, you might have been receiving free products of the company, enjoying any service of the company free of cost because you project their products and services online as a paid blogger.
If you have been hired to purposefully project certain products and services of a company, you should state it in the blog disclosure policy page clearly. This is due to the need that public or readers should know that the written work is done under a commercial compensation scheme and the writer is getting paid for promoting the products/services of any other party.
You should be honest and give all details of the compensation that you receive as a blogger. Since cyberspace is full of information and blogs of all sorts, the readers as consumers of this information have their right to know whether the information is made available through paid efforts and the company or a person who has been paying the blogger to achieve a certain target or agenda.
Giving details of the compensations you receive against your work does not affect your reputation as a writer, but it allows people to consume information and make an opinion while keeping in mind the credibility of information. This is to aware readers about the intentions behind the post and the main party that is responsible for promoting the post.