(Extracted from the article "How to Interact Respectfully with Bhikkhus - Basic Etiquette in Theravāda Buddhism")
Theravāda Sangha members can only accept offerings of allowable requisites (such as robes, food and drinks, medicine, and daily necessities.) They cannot accept and possess money in any form (such as in the form of cash, "ang baos" (red packets), cheques, credit cards etc). If a bhikkhu were to accept monetary offerings, he would be considered to have transgressed his precepts. One should also not offer inappropriate items such as cigarettes, liquor, disallowed meat, cosmetics, weapons, gold, silver and precious stones.
HOW TO OFFER ALLOWABLE REQUISITES
Bhikkhus cannot request for any items from any lay person (except blood relatives) who have not initiated his or her invitation for offerings (the exception being a bhikkhu who is ill and is requesting for offering of medications). If one is keen to make offerings but is uncertain about what a bhikkhu requires, he could invite the bhikkhu and ask if he (the bhikkhu) needs any allowable requisites.
Alternatively, he could seek help from the bhikkhu's kappiya (attendant). As the kappiya would have a better idea of what requisites the bhikkhu requires, the donor could seek his assistance in arranging (purchasing) allowable requisites to offer to the bhikkhu. After the donor has passed the money to the kappiya, he would need to extend a verbal or written invitation to the bhikkhu, stating thus:
How to offer Allowable Requisites to the bhikkhu
Note: If you know who is the kappiya (kappiyakāraka) of the bhikkhu, please mention the name in the ............. (kappiya’s name). If you don't know who is the kappiya of the bhikkhu, then please ask the bhikkhu first ''Who is your kappiya?'' and mention this name in the ............. (kappiya’s name). (The bhikkhu must answer only the name of his kappiya: must not say ''to give to whom''.)
I/We wish to offer bhante allowable requisites to the value of $xxx. If you need any allowable requisites, please request them from your kappiya ........................ (kappiya’s name).
For a copy of the above invitation wordings in Chinese and Burmese language, please download from here.
(* note from PAMC: in PAMC, we would collect the money for purchasing of bhikkhu's requisites on behalf of the kappiya and the kappiya will extend the verbal invitation to the bhikkhu regularly with the cumulated amount)
If both the donor and the kappiya failed to extend the invitation to the bhikkhu, then the bhikkhu could not request for any items even if he has a need. In such a circumstance, both the bhikkhu and the donor would not benefit from the arrangement.