Thousands of Lang Registry staff are due to walk out for 48 hours in a row over government consultations on the future of the 150-year-old agency, which includes an option of privatising it.
The industrial action could affect those buying and selling property.
Business minister Michael Fallon was still working through responses to the consultation document.
The government has argued that a proposed private company would serve the property market "more effectively [with] greater flexibility to operate".
The Department for Business said it intended to retain a separate Office of the Chief Land Registrar within government, which will mainly perform regulatory and fee-setting functions.
But the Public and Commercial Services Union (PCS) is worried that the move could lose hundreds of jobs.
"To avoid the charge that its consultation was a sham to help it drive through privatisation, the government must scrap it and start again with a genuine option for the Land Registry to stay in the public sector," said Mark Serwotka, general secretary of the PCS.
"There is strong opposition to this move from staff, lawyers and property experts, who recognise the need for retaining the independence of what is a successful and popular public service."
The PCS claimed that more than 3,000 Land Registry workers would walk out in protest and said the organisation had a near 100% customer satisfaction rating.
A spokeswoman for the Land Registry said: "We will continue to engage with our trade union in order to see if we can find a way to work together in order to prevent industrial action.
"However, in the event of a strike we will endeavour to ensure that there is minimal disruption to the services we offer to our professional customers and the public. We apologise for any inconvenience that may be caused."