Shulchan Arukh, Yoreh De'ah 347

שלא לעורר על מתו שלשים יום לפני הרגל. ובו ג' סעיפים:מי שמת לו מת לפני שלשים יום הסמוכים לרגל לא יספדנו משיכנסו שלשים יום הסמוכים לרגל ואפי' יש לו הספד בלא זה כגון שמת לו מת בתוך שלשים שמותר לספדו ואפילו מת ערב הרגל אסור להספיד עמו על המת שמת לו לפני שלשים יום קודם המועד:

One who suffered a bereavement prior to thirty days before1Lit. ‘close to.’ a Festival, should not make a lamentation for him2The dead. from [the time] that the thirty days before1Lit. ‘close to.’ the Festival begin.3Lit. ‘enter.’ M.K. 8a; Y.M.K. I, 5(80d). Since the dead will not be put out of mind for at least thirty days (M.K. ibid. in accord with Samuel), and if a lament is held during this period, his grief and bitterness would be roused during the Festival. This applies even if the lamentation is performed gratis (cf. opinion of Rab ibid.). Tur a.l. Prior to Rosh Hashana and Yom Kippur it would be permissible — P.Tesh. [This applies] even if he has to make a lamentation4Thus RaBaD. [in any case] without this, e.g., [if] he suffered [another] bereavement within the thirty days [of the Festival], for whom it is permissible to make a lamentation, even if he died on the eve of the Festival,5For in the case of the new bereavement his grief would not be roused any more than it is, which would not be the case were he to make a lamentation for the old bereavement too, as a result of which the festive spirit of the Holiday would be greatly diminished. [nevertheless], it is forbidden to make a lamentation along with him6The new dead. for the bereavement that he suffered before thirty days prior to the festive season.7If a renowned scholar dies, it is permissible to make a lamentation even within thirty days of the Festival, on accoun of the honour which we are dutibound to extend towards him — P.Tesh. The entire ruling as stated here is also found in O.Ḥ. § 547, 3.

מי שבאה לו שמועה בתוך שלשים יום קודם הרגל נראה לי שמותר לספדו אף על פי שהיא רחוקה:

One who received tidings [of death] within thirty days before the Festival, it seems to me that it is permissible to make a lamentation8Since the grief is fixed and will not be roused any more than it is on account of the lament. Consequently, this case is similar to a new bereavement suffered within thirty days prior to the Festival at which time it is permitted to hold a lament (cf. supra par. 1). for him,9The dead person. although it is [already now] distant [tidings].10e., the death occurred before the thirty days prior to the Festival. This law is based by Caro on Y.M.K. ibid. and is also found in O.Ḥ. ibid. par. 4.

מה שאנו נוהגין בתשלום השנה לקונן ולהזכיר נשמות נראה לי שאינו בכלל זה ומותר לעשותו סמוך לרגל:

Our accepted practice upon completion of the [first] year to bewail and to memorialize the souls [of the dead],11Thus was the custom in Spain. seems to me, is not included in this principle,12 supra par. 1. The reason was that this memorial marked the conclusion of the mourning period at which time it was customary to change from dark to light garments. and it is permissible to do so close to the Festival.13e., within the thirty days. It is permissible to memorialize the souls of departed ones for the first time, even during the Festival — ShaK. For the source of this ruling cf. B.Yos. to O.Ḥ. ibid. par. 5. One is permitted to recite the Yizkor Memorial prayers during the first year after death and must not wait until a complete year has passed — Sukkath Shalom. It is customary for those whose parents are living to leave the Synagogue during the Yizkor Service so as not to disturb those who recite these prayers — Minhage Yeshurun.