Marriage is a life time commitment that involves loving (as a verb not a noun) your spouse through everything. It is hard work and if you stop working your marriage dies. You will not always love (as noun) your spouse, or even like them. There will be times when you can see no benefit of any kind and times of heartache. If you honor your vows and love (as a verb) your spouse all you life it is the most rewarding relationship two people can have. It is a source of happiness, joy, peace, support, and contentment that you cannot understand unless you have married, and given yourself completely to your spouse and determined to spend the rest of your life doing so, no matter what. If you are weighing the financial benefits of marriage then you have neither the love nor the commitment to honorably do anything but stay single at this time.
If you are asking for purely intellectual purposes, the financial benefits vary from couple to couple and change over the course of a marriage.