Tax Return and Letting Agent

[JDHK]

I am a NRL with a UK flat which is let. There have been no problems with my tenants paying their rent, but in the middle of last year my letting agent failed to to pass on 3 months rent to me (totalling £3900). I engaged a solicitor to pursue the debt but the agent subsequently went into liquidation. I have lodged a Proof of Debt form with the liquidator (covering the £3900 in lost rental plus £1800 security deposit which the agent was holding) but there seems to be very little chance of me recovering this money.
My question is how do I account for the above on my SA tax form which will no doubt be winging its way to me soon? I never received the £3900 so it would seem logical that I do not have to include it as rental income but I am not sure if this is the correct interpretation for tax purposes.
Also does the £1800 come into it anywhere? (I have paid £1800 to my new letting agent to replace the lost security deposit).
Any advice on the above gratefully received.

[King_Maker]

You may have a problem if he is your Agent (very likely).

It is not a bad debt, as the tenant has paid the rent due.

Did the Agent deduct tax from the other rent, or has HMRC given you exemption?

Were you not insured against this?

[Poppy]

Was this agent a member of NAEA, ARLA or RICS? If not, suggest that any future letting agent employed comes under one of these umbrellas. Be careful, you don't want it happening twice.