There are some useful comments in this thread but maybe it is worth collecting them in one place and being a bit more precise about the tenancy rules and their consequences:
1) Notice of termination
If your landlord wants you to leave he/she must serve you with a notice of termination. In order to be valid a notice of termination must:
a) be in writing
b) be signed by the landlord (or an authorised agent)
c) specify the date of termination
d) state the reason for termination (if a tenancy has lasted more than six months)
e) state that any issue with the notice must be referred to the PRTB within 28 days from the receipt of the notice.
f) The notice can be posted to you, be given to you in person or left for you at the property.
2) Terminating a tenancy
Landlords can ask tenants to leave without giving a reason during the first six months of a tenancy. Landlords can terminate a tenancy that has lasted between six months and four years (a Part 4 tenancy) only in the following circumstances:
a) After 3 and ½ years
b) If the tenant does not comply with the obligations of the tenancy
c) If the property is no longer suited to the tenants’ needs (e.g. overcrowded)
d) If the landlord needs the property for him/herself or for an immediate family member
e) If the landlord intends to sell the property
f) If the landlord intends to refurbish the property
g) If the landlord plans to change the business use of the property (e.g. turn it into offices).
3) Notice periods
The length of notice depends on the length of the tenancy.
Length of tenancy Notice by landlord
Less than 6 months 4 weeks (28 days)
6 months to a year 5 weeks (35 days)
1 – 2 years 6 weeks (42 days)
2 – 3 years 8 weeks (56 days)
3 – 4 years 12 weeks (84 days)
4 years or more 12 weeks (From September 2008, 16 weeks (112 days))
Landlords can give less notice if the tenants are not keeping their obligations (28 days) or if there is serious anti-social behaviour (7 days). Anti-social behaviour includes violence, threats or intimidation as well as any persistent behaviour that interferes with neighbours.
If you do not pay your rent a notice of termination may be served, only if the rent due has still not been paid 14 days after you get written notification from your landlord of the amount owing.
Landlords and tenants can mutually agree shorter notice periods but they can only do so at the time they decide to terminate the tenancy. It is illegal to agree a shorter notice period at the start of the tenancy. That is your Part 4 rights take precedence over your lease. Landlords and tenants can also agree longer notice periods but the maximum is 70 days when the tenancy has lasted less than six months.
Clearly your landlord must serve you with 56 days notice, in a valid written format and must use also use one of the valid reasons for termination listed above. Your landlord seems to want to use the property for an “immediate family member” which he is perfectly entitled to do. That is option 2d) above. However if your landlord claims termination of the lease to house an immediate family member and subsequently does not carry out the intention you can report him/her to the Private Residential Tenancies Board (PRTB). The PRTB will investigate your claim and take further action as appropriate.
As part of your Part 4 rights you are entitled to stay in the property for a total of 4 years or 3 1/2 years after your 6 month probation, or in other words your landlord must give you security of tenure in 4 year cycles and one of the few reasons he can terminate the lease is option 2a) above. However there are some potentially very serious traps. You must remember that the onus is on you as the tenant to advise your landlord of your intention to renew the lease in a window of 3 months to 1 month of the expiry of your 1 year fixed leases. Otherwise your landlord is entitled to assume you have no intention of extending the lease and will commence the expenses of finding a new tenant and potentially signing a legally binding lease with that new tenant. If you should subsequently decide to exercise your Part 4 rights and de-facto renew your lease by overstaying for example a 4th year you are exposing yourself to potentially horrendous legal costs as your landlord is entitled to seek compensation from you for any expenses incurred by him in sourcing a new tenant and then subsequently breaking the legally binding lease he has just signed with your replacement.
So to conclude, you and the landlord seem to be in a bit of a race, but either way you need to start looking for a new place. You need to inform your landlord of your intention to extend at your first opportunity which is 01 July 2011. Your landlord cannot refuse. However, he can still serve you with 56 days proper written notice of his intention to house an immediate family member. He may be lying and may never carry out this intention in which case you can take appropriate action to seek compensation with the PRTB. Problem is that this is retrospective and you are going to be out of the property. The best you can probably hope for is 56 days breathing space and if your landlord really is as dumb as he sounds a fat compensation for your troubles from the PRTB further down the road when he doesn’t move in an immediate family member. I would start looking for a new place now.