Claudia Telles scored a $30,000 raise at a Chicago-based hospital.

The 28-year-old went from making $41,000 on the business-operations team to $72,000 as a quality specialist — and she plans to double her new compensation in the next two years.

A crucial part of negotiating such a substantial raise was steering clear of a common yet costly mistake: disclosing your current salary.

“I never brought up my old salary,” Telles tells Business Insider.

Despite transitioning within the same company, she was working with a separate HR team than she did when she first applied three years ago, meaning she was able to keep her $41,000 salary confidential.

Revealing your salary history has the potential to negatively affect your income for your entire career.

“How are you ever going to increase your earnings if every time you change jobs, you get a tiny raise over what they paid you at the last place?” writes Liz Ryan, founder and CEO of consulting firm Human Workplace, in a post on LinkedIn. “We’ve gotten used to the idea that the question ‘What were you earning before?’ from a prospective employer is perfectly reasonable. It’s not, of course. Your personal finances are your business.”

How do you avoid the question without hurting your chances of landing the job?

Telles emphasized that the position she was applying for was completely different from her current role, rendering her salary irrelevant.

She then focused on presenting her value to the company.

“I was really able to showcase that I knew what was going on and could do the job effectively,” she told Business Insider. “I told them that for the type of work that needs to get done — and will get done — this is the type of salary that would be appropriate.”

One recruiter recommends using the line, “I’d be glad to help you assess what I’d be worth to your business by showing you what I can do for you, but my salary is personal and confidential, just as the salaries of your own employees are.”

Remember that there’s nothing wrong with politely but firmly declining to disclose your salary history. You never know — it could be the difference between a $5,000 raise and a $30,000 raise.

SEE ALSO: 7 steps to salary negotiation from a 28-year-old who made a $30,000 leap

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