There is no single number; each loan program flags large deposits by its own formula, and the major ones now key off your monthly income. - Conventional (Fannie Mae and Freddie Mac): a large deposit is a single deposit over 50% of your total monthly qualifying income. A household qualifying with $10,000 a month would generally need to source any single deposit over $5,000. Freddie technically only requires sourcing on a purchase when the money is needed for your down payment or closing funds, but expect the question either way. - FHA: same idea under current guidelines, a single deposit over 50% of your total monthly effective income gets flagged. (Older FHA files used a percentage of the property's value; the income-based test is the current one.) - Jumbo: each lender sets its own rules, and any lender can add stricter overlays on top of the agency guideline, so confirm current requirements with whoever is handling your loan. Sourcing simply means showing where the money came from: a pay stub, a documented sale, a transfer between your own accounts. Easy when you keep the paperwork. The cleanest approach is to avoid unexplained cash deposits in the couple of months before you apply, because large cash you cannot tie to a clear source is the one deposit underwriting cannot use.