Many women have said “I would love to be a surrogate but I have had my tubes tied.” They are very surprised to learn that, indeed, a tubal ligation will not prevent them from helping a couple become a family!
A tubal ligation is a permanent form of birth control, true. After this procedure has been performed, an egg cannot move from the ovary through the tubes (a woman has two Fallopian tubes), and eventually to the uterus. Also, sperm cannot reach the egg in the Fallopian tube after ovulation (release of an egg from the ovary.) To become a Gestational Carrier, where you are not using your own eggs or tubes and therefore a woman can become a surrogate even if her tubes have been tied. (You cannot become a traditional surrogate where you would be using your own eggs.)
If this is the only thing holding you back from becoming a surrogate, I suggest that you find an agency and see what else you need to do to qualify as a gestational carrier. You will be glad you did!