The SDLP is expected to vote against the power-sharing Executive's proposed budget when it goes to a vote in the Assembly today.
The party has already voted against the Programme for Government, although its single minister Margaret Ritchie was bound by her code of office to support it.
She will also have to vote for the budget today, but her party colleagues are expected to oppose it due to concerns about water charges, health and reform of primary-level education.
Despite the move, the SDLP intends to remain part of the power-sharing Executive rather than going into opposition.