The UK's second biggest mortgage lender has increased the deposit homeowners need to qualify for its best rates to 25% of a property's value. Nationwide Building Society has decreased the maximum loan to value (LTV) ratio people need to qualify for its best deals from 90% of a home's value to 75%. When you're on the look out for a new home, you need cash. A lot of it. Most homes today have down payments that are more than what the buyer can afford right then and there. The solution for this? A mortgage.