Joint tenancy or tenancy in common? — it changes what happens next, not whether you can use DJP
It is still worth confirming how the property was held before you start — not because it changes the form (it does not: form DJP removes the deceased's name whichever way the property was owned), but because it decides what happens to the deceased's share, and what you will need to do before the property can be sold.
How to check the title
Order a copy of the official title register from HM Land Registry (at gov.uk/search-property-information-land-registry — costs £7 online).
Look at the Proprietorship Register section (usually the B section).
If you see both names as registered proprietors and no Form A restriction, it is almost certainly a joint tenancy.
If you see the words 'RESTRICTION: No disposition by a sole proprietor of the registered estate' or 'Form A restriction', the property is held as tenants in common.
The Form A restriction
A Form A restriction reads: 'No disposition by a sole proprietor of the registered estate (not being a trust corporation) under which capital money arises is to be registered except under an order of the Registrar or of the Court.'
This is the standard restriction used when property is held as tenants in common.
If you see it, you can still send form DJP. The restriction stays on the register after the deceased's name is removed.
It means the deceased's share belongs to their estate rather than passing to you outright — and that before the property can be sold or mortgaged, either a second trustee must be appointed to act alongside you, or, if the share has since passed to you, you can apply to cancel the restriction (form RX3, with a statement of truth on form ST5).
What if you are unsure?
Look at the original purchase documents (transfer deed, TR1 form, or conveyance if old).
There should be a box that was ticked for 'joint tenants' or 'tenants in common in equal shares'.
If you cannot find the original documents, ask the conveyancing solicitor who acted on the original purchase — they are required to keep records for 6 years (12 years for property transactions).
Severed joint tenancies
Even if the property was originally purchased as a joint tenancy, the joint tenancy may have been severed later by a written notice, a deed, or conduct (such as one party attempting to sell their share).
A severed joint tenancy converts to a tenancy in common.
Check the title register for any restriction or entry referring to 'severance of joint tenancy' or 'Form A restriction entered on [date]'.