It is real simple. Typically at the time you close on a mortgage loan you will sign a document called Transfer of Servicing. It will indicate the percentage of the loans the lender has sold over the last 3 yearsu2023 it will typically be 100%. Mostly all loans have their servicing sold immediately as lenders are not set up to collect mortgage payments so you will get a letter before your 1st mortgage payment saying your loan has been sold and you will get a welcome letter from your new servicer stating where to send your payment.