Entry in progress—B.P.
     
Wikipedia: Golden hello
A Golden hello is a bonus offered by hiring firms if the hired joins the company from a rival firm. It is very similar to the traditional joining bonus offered by firms but will be offered usually for rival firm employees luring them into a firm.
 
Typically, “Golden hellos” are offered only to high-ranking executives by major corporations and may entail a value measured in millions of dollars.
 
In the UK a ‘golden hello’ is a financial incentive to teachers training in shortage subjects for secondary education. The value varies according to the subject with Science and Maths attracting £5000 where as music is offered £2500. The incentive is paid by the TDA teacher development agency.
 
Investopedia
What Does Golden Hello Mean?
A signing bonus offered by a securities firm to a key executive from a competing firm.
 
The Free Dictionary
golden hello
n
(Business / Industrial Relations & HR Terms) Informal a payment made to a sought-after recruit on signing a contract of employment with a company
 
(Oxford English Dictionary)
golden hello n.  [after golden handshake n.] a substantial sum offered to a senior executive, etc., as an inducement to change employers, and paid in advance when the new post is accepted.
1983 Observer 15 May 15/8   Following the ‘golden handshake’, the ‘*golden hello’ is taking root in British industry. Being paid a handsome lump sum before you even start a new job may sound too good to be true. But, last year alone, 50 top directors got such ‘golden hellos’.
1985 Listener 6 June 8/3   They’re often tempted away to a rival by a ‘golden hallo’: a sort of transfer fee on top of a sizeable salary increase.