Directive 329 defines the grace loan: a deferral period at the start, after which the loan is repaid by the Spitzer schedule. The deferral may cover principal only (partial grace) or principal and interest (full grace). It is mostly used when you expect your income to rise or a payment to arrive, for example the sale of another home.
Grace lowers the first payments but not the cost: interest runs on the full principal during the deferral, and the payment after grace is higher than on a loan without grace over the same total term, because fewer months remain. For the payment-to-income test the bank uses the payment expected after the grace period ends.
The pitfall is borrowing against the low first payment. Ask the bank exactly how interest is handled during full grace, and check that you can afford the payment after it.
Example
₪500,000 at 4% over 25 years. Without grace the payment is ₪2,639. With a 2-year partial grace you pay ₪1,667 of interest for 24 months and then ₪2,774 for 23 years, about ₪13,800 more interest in total (about ₪305,600 instead of ₪291,800). The bank tests the payment-to-income ratio on ₪2,774, not on ₪1,667.