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Commercial Property

Side Letters to Commercial Leases

side letter commercial lease

If you are leasing a commercial property you may encounter a ‘side letter’ in addition to the lease itself.

A side letter in such a situation is used by a landlord and tenant-as it is signed by both parties-to modify the terms of the lease itself, generally on a temporary basis. This would be done to confidentially vary the terms of the lease and prevent any knock on comparable consequences for the landlord from other tenants in a development.

An example of this would be a concession in relation to rent for a temporary period of time.

This concession would not be in the public domain as the rent might be if the lease was lodged in the Registry of Deeds or details registered with the Commercial Lease Register of the Property Services Regulatory Authority.

Some points to consider

  1. The time period or special event which is to be covered by the side letter should be clear if the concession is to be temporary and for the particular lessee
  2. If the lease itself contains an ‘entire agreement’ clause then the side letter should be mentioned in the entire agreement statement
  3. If the side letter is agreed and granted at a different time from the lease itself then there should be some consideration given for the side letter, even a nominal sum
  4. The landlord needs to be careful that the granting of the side letter will not inadvertently let a guarantor off the hook
  5. Is this side letter to be binding on a future landlord if the sells the building? Is the side letter to be personal to the existing lessee and not assignable to a new tenant?
  6. The side letter will be terminated if any provisions of the lease are breached-for example, late payment of rent

A problem may arise if the breach of the lease leads to the side letter being set aside as this may amount to a penalty for the tenant which is disproportionate to the loss suffered by the landlord for the breach. If that is the case the side letter may be unenforceable if challenged.

Provided the penalty is proportionate the side letter is likely to be enforceable, however.

Side letters will usually bind a landlord’s successor in title and should, therefore, be disclosed to a any future purchaser. For this reason any side letter should be kept with the lease so that it is disclosed on sale. If it is not disclosed a future purchaser will probably succeed in a claim for misrepresentation and the cost of complying with what has been agreed in the letter.


The leading case in this area is Vivienne Westwood Limited v Conduit Street Development Limited, a UK case. This decision is not binding on Irish Courts but would probably be persuasive as the Irish and UK landlord and tenant law is broadly similar and the decisions tend to be similar.