NOT true, for Corpus at least. You won't get it, we all tried when we got to Corpus.
I was told by the PSD guy at TW-4 that you get per diem from the date your original commissioning/TDY orders were modified for a PCS to Corpus to the date you showed up here in Corpus. Also, I had to get a letter from Fairfield Lakes saying how much rent I paid, and we are supposed to get reimbursed for that since we were on TDY the whole time. This is kind of blowing my mind, but I guess I'll wait and find out if I get that $6K extra payday or not. Knock on wood...