The number of payments you can miss on your mortgage before the foreclosure process begins depends on a few different factors. Because of this, there is no one-size-fits-all answer to this question.
Primary among the factors that affect how long a borrower can go without paying before being forced into foreclosure are the practices and policies of your lender. If the lender has a large portfolio of low-risk loans, it may be more lenient regarding missed payments. Often, it will forgive an occasional missed payment and may not refer your situation to the housing authorities until you miss four or more payments. However, if the lender has a portfolio of high-risk loans, the possibility of foreclosure proceedings beginning even after just two missed payments is high. Even if you are a low-risk borrower, the proceedings may be triggered by standards due to the overall default risk of the mortgage pool owned by the lender.
The general state of your local housing market is another factor that plays a role in the timing of foreclosure proceedings. If the neighborhood or region has many pending foreclosures, it is likely you will be able to stay in your home longer, as local housing authorities may be backlogged and lacking resources to process so many cases. There have been situations where people missed 10 or more monthly payments before finally losing their home.
If you are in default, your mortgage servicer should contact you multiple times to attempt to alleviate the situation. Typically, by the 36th day after your last payment, the lender contacts you by phone. By the 45th day after you miss a payment, your mortgage servicer must contact you in writing and provide information regarding the options available to you.