Martucci says even if a credit union doesn't have centralized operations, the size of the credit union can impact its ability to provide individualized attention. "Big entities just don't work as well as small ones," he says.Some Realtors say that a large credit union can be just as slow to respond to customer needs as a large bank. Toler says that while credit unions use the same computer system to underwrite their mortgage as banks, credit unions keep about 25 percent of their loans in their portfolio rather than selling them to investors. Maintaining a substantial portfolio of loans allows credit unions to be more flexible with customers. "In a credit union, we can use old-fashioned banking methods for our members," says Toler. "For example, if a 20-year member of the credit union is rejected by the desktop underwriting system because of a slightly low credit score, we can evaluate that loan personally and choose to keep it in our portfolio." Individualized mortgage approvals, closing cost assistance and low lender fees are all reasons to consider becoming a member of a credit union. However, be sure to compare all your options between a bank, a direct mortgage lender and a credit union to see which works best for your needs.