Siman 469
Presented here for study, not as a practical ruling. The Shulchan Aruch rules by Sephardi custom, the Rema's glosses by Ashkenazi custom, and the Kitzur follows Ashkenazi custom. For a practical question, ask your rabbi.
א אָסוּר לוֹמַר עַל שׁוּם בְּהֵמָה, בֵּין חַיָּה בֵּין שְׁחוּטָה; בָּשָׂר זֶה לְפֶסַח, לְפִי שֶׁנִּרְאֶה שֶׁהִקְדִּישׁוֹ מֵחַיִּים לְקָרְבַּן פֶּסַח, וְנִמְצָא אוֹכֵל קָדָשִׁים בַּחוּץ; אֶלָּא יֹאמַר: בָּשָׂר זֶה לְיוֹם טוֹב. הַגָּה: וּגְדִי מְקֻלָּס פי' שָׁלֵם עַל רֹאשׁוֹ וְעַל כְּרָעָיו וְעַל קִרְבּוֹ, אַף עַל פִּי שֶׁלֹּא פֵּרֵשׁ וְאָמַר זֶה לְפֶסַח, אָסוּר לַעֲשׁוֹתוֹ (טוּר) כְּדִלְקַמָּן רֵישׁ סִימָן תע"ו; אֲבָל מֻתָּר לוֹמַר: חִטִּים אֵלּוּ לְפֶסַח.
1 It is prohibited to say over any cattle, whether living or slaughtered, "this meat is for Passover" due to the fact that one appears to be consecrating his animal as his Paschal lamb, and he thereby eats consecrated items outside the permitted area. Rather, one may say "this meat is for the Festival". Rema: and it is prohibited to roast a kid whole (—with its head, its legs and its entrails at its side) even when one does not specify "this meat is for Passover". However, [with regard to wheat] one may say "this wheat is for Passover".