Independent Tasmanian senator Jacqui Lambie has fired an angry salvo at Federal Treasurer Joe Hockey, accusing him of failing to consult cross-bench politicians about key measures in the 2015 Budget.

In a sign that the government faces another uphill struggle getting spending cuts and revenue measures passed in the Senate, Ms Lambie warned Mr Hockey that she would oppose planned changes to family tax benefits.

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The government is proposing to tighten eligibility rules and the level of childcare support for many families.

The planned changes mean that tax benefits would be cut for some families when a child turns six.

“It costs more to bring up a child as they get older,” Ms Lambie said.

Senator Lambie said the government had not consulted independent senators about this year’s budget measures.

“No one’s done any consultation with me,” she said.

“I don’t think anything’s different (this year) and I don’t hold out much hope.”