Up-front charges for migrants to use the NHS are unfair on nurses and are tearing families apart, union leaders are warning.
The Royal College of Nursing wants the £200 overseas surcharge scrapped for nurses coming to work in the NHS.
It said the policy was "shameful" and is highlighting the case of a Kenyan nurse who sent two of her children back to Africa because of the charge.
The charge was introduced in 2015 for non-EU migrants to boost NHS funding.
The £200 charge is applied per family member for every year on the main sponsor's work permit.
It is due to increase to £400 later this year and there are suggestions that post Brexit it will be applied to EU nationals too.
The issue will be debated at the RCN's annual conference which is taking place in Belfast this week.
'I had to send my children back to Africa'
Evaline Omondi is due to address delegates next week.
She said she was landed with a bill of £3,600 to cover a three-year period for two adults and four children.
It forced her to take her two youngest children, aged six and eight, out of school and send them back to Kenya.
She said it was an "awful moment".
"We could not meet the cost and my children had to move back to Kenya.
"A family who came together is now in pieces, scattered all over the place.
"I try to speak to them on the phone before they sleep but it is hard with the time difference and my work so sometimes I don't get to talk to them."
The RCN says there are 25,000 nurses from outside the EU working for the NHS.
RCN general secretary Janet Davies said: "We are proud as a profession to have the best and brightest from over 200 countries around the world.
"But the government now seems hell-bent on showing that they're no longer welcome."
The Home Office said the surcharge had an important role to play, generating income that goes directly to the NHS and offered access to comprehensive care "at a much lower cost" than is available in other countries.
"The government fully recognises the contribution that international professionals make to the UK and to our health service," a spokesman added.