Shulchan Arukh, Yoreh De'ah 347

<b>שלא לעורר על מתו שלשים יום לפני הרגל. ובו ג' סעיפים:</b><br>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 before a Festival, should not make a lamentation for him from [the time] that the thirty days before the Festival begin.. 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 lamentation [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, [nevertheless], it is forbidden to make a lamentation along with him for the bereavement that he suffered before thirty days prior to the festive season. 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 lamentation par. 1). for him, although it is [already now] distant [tidings]. 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], seems to me, is not included in this principle, 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. 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.