The most common deposit to write for buying a house in the United States is the down payment. This is the initial upfront payment made by the buyer to the seller, typically representing a percentage of the home's purchase price. The standard down payment is 20% of the home's value, but many buyers opt for lower percentages, such as 10% or even less, depending on the loan type and the lender's requirements.

The reason for this is multifaceted. Firstly, a larger down payment can lead to a lower interest rate on the mortgage, which can save the buyer thousands of dollars over the life of the loan. According to the Consumer Financial Protection Bureau (CFPB), a higher down payment can also reduce the risk for the lender, as it indicates that the borrower is more committed to the purchase and has a greater stake in the property. This can result in more favorable loan terms.

Additionally, a down payment of 20% or more allows the buyer to avoid private mortgage insurance (PMI), which is an extra cost that protects the lender in case the borrower defaults on the loan. According to the National Association of Realtors (NAR), PMI can add an average of $100 to $200 per month to a borrower's mortgage payment, depending on the loan amount and the PMI rate.

Moreover, a down payment demonstrates financial stability and responsibility, which can be a significant factor in the lender's decision to approve the loan. According to a survey by the Federal Reserve, 47% of consumers believe that a down payment is the most important factor in getting a mortgage approval.

It's important to note that while a 20% down payment is ideal, it's not always feasible for all buyers. There are various loan programs available that allow for lower down payments, such as FHA loans, which require as little as 3.5% down, and VA loans, which are available to veterans and active-duty military personnel with no down payment required. These programs are designed to help more people achieve homeownership, but they often come with additional requirements or higher interest rates.

In conclusion, the down payment is the primary deposit to write for buying a house in the United States due to its impact on interest rates, PMI, and the lender's perception of the borrower's financial stability. While a 20% down payment is ideal, there are alternative options available for those who cannot afford it.