If the employer or hiring manager raises the issue of salary in an interview, you can discuss it then. If not, a job offer is typically made verbally before a formal written offer is received, and this verbal offer stage is the best time to negotiate, since you are now firmly positioned as the employer’s preferred candidate.
You may be prepared to discuss your case, but if upon receiving the offer you need to gather your thoughts, it is perfectly acceptable to thank your recruiter or the hiring manager for the offer, affirm your enthusiasm for the role, and ask for a few hours or one day to consider it. You should not verbally agree to an offer and then ask to negotiate the salary - or any other aspect of the role - once you have received the contract.
During your negotiations, keep the lines of communication open. Tell your recruiter or the hiring manager that you are very interested in the position, but that you would like to negotiate. Discuss openly and professionally your opinion and desired outcome, and support your salary view with evidence from a salary guide, such as the 2012 Hays Salary Guide, to show that your expectations are aligned with current market rates.
Speak to your recruiter and listen to their advice. Remember, we are experts in recruiting and have the professional know-how to advise you on current market trends. We will negotiate on your behalf with the employer, without the risk of you jeopardising the offer.
Do not expect an immediate response; the hiring manager will need to gain approval from their manager for any revision to an offer. But, once they respond, you should accept or reject the offer in a timely and professional manner.