Does a flat management company need to file a CT600?

By Ben Davies · Updated 26 September 2026

Possibly — a company limited by guarantee, which almost every flat management company and, by law, every RTM company is, doesn't get any special exemption from Corporation Tax the way an LLP does. It's within Corporation Tax scope like any other company.

In practice, plenty of flat management and RTM companies never file a CT600 at all, because HMRC writes to them confirming that a return isn't needed. That's a genuine, valid decision by HMRC, based on the company having no income for HMRC to tax — not a loophole or an oversight. If you've had that letter, it governs: you don't need to file unless HMRC later asks you to.

If HMRC does want a return, it says so by sending a notice to deliver one — and a notice, once sent, must be answered even for a dormant period. A dormant company then files a nil CT600: no income and no tax to pay. We support filing it, but as with any company on DormantFile, you enter the CT600 details yourself: your UTR, your accounting period, your HMRC Government Gateway login at the point of submission. We don't work out whether HMRC wants a return from you — that's between you and whatever HMRC has told the company — and while the statutory deadline for any period you've entered is tracked and reminded, HMRC's letter is always definitive. See do I need to file a CT600 for a dormant company? for the general decision tree.

Whether or not a CT600 is due, the company still owes its annual accounts to Companies House — dormant, if service charges stay off its own books, or micro-entity if they don't. See is a flat management company dormant? for that test.

Read the full guide: How to file dormant accounts for a flat management or RTM company