In the Philippines, the U.S. Embassy does not accept a joint sponsor. A joint sponsor is your solution if your income is too low. A joint sponsor is someone who has adequate income and signs a formal, legal document saying they will support your fiancé in the United States. That’s not possible with a K-1 in the Philippines. As far as we know, it’s the only country that doesn’t allow a joint sponsor for a K-1. In other countries, you can use a joint sponsor for a fiancé. In the Philippines, you can for a spousal visa but for a fiancé you cannot.
If your income is not adequate and you want to bring your fiancé here from the Philippines, you either need to increase your income, find another job or use assets. One of the toughest parts of the process for many applicants is the financial requirements. If you have the required minimum income, then your case has a much higher chance of success. Where it gets tricky is when your income is marginal or you’re self-employed and so your income is below the required level.