Intro
For many landlords, the hardest part isn’t the tax.
It’s knowing what to do first.
Because once you realise rental income hasn’t been reported…
the question quickly becomes:
👉 “Do I need to tell HMRC?”
And more importantly:
👉 “How do I actually do that properly?”
This is where a lot of people feel stuck.
Not because they don’t want to deal with it — but because they don’t want to get it wrong.
If you’re only just starting to look into this, you may find it helpful to understand what happens when rental income hasn’t been reported:
What Happens If Rental Income Was Never Reported?
What “Telling HMRC” Actually Means
This isn’t just a message or a quick update.
It’s the start of a formal process.
When you tell HMRC about undeclared rental income, you are:
- confirming that income hasn’t been reported
- providing details across multiple years
- explaining how the situation arose
And once that process begins,
you’re expected to support what you submit.
At this stage, many landlords also start asking:
“How much is this actually going to cost?”
If that’s something you’re thinking about, I’ve explained how the figures are built up in this guide:
How Much Tax Will You Pay on Undeclared Rental Income?
Why This Needs to Be Done Carefully
One of the biggest mistakes is rushing this step.
It’s natural to want to “get it sorted quickly.”
But without a clear understanding of your position, that can lead to:
- incomplete figures
- incorrect timelines
- assumptions that don’t hold up
And once information is submitted,
it’s not always easy to step back and correct it properly.
What Needs to Be Done First
Before contacting HMRC, the priority is understanding your rental position.
That means:
- when the property started being rented
- how many years are involved
- how much income was received
- what expenses can be claimed
Without this, you’re working from guesswork.
And that’s where problems usually start.
This is also where understanding how far back things may go becomes important.
HMRC Going Further Back Than You Expected? What It Means for You
If You’d Rather Watch Than Read
If you’d rather watch than read, I’ve explained how this works in the video below: Video is live tomorrow
Once you understand this properly, the next step becomes much clearer.
What the Process May Involve
Depending on your situation, telling HMRC may involve:
- preparing figures across multiple years
- submitting a disclosure
- responding to follow-up questions
- agreeing the final position
This isn’t about one number.
It’s about building a clear and supported picture.
Why Timing Matters
Leaving this too long can make things harder.
Over time:
- records become harder to find
- details become less clear
- timelines become more complex
But rushing without clarity can also create problems.
The balance is:
👉 understanding first
👉 acting second
At this point, the question is no longer just how to tell HMRC…
but when and in what order to deal with things.
If you’re also thinking about selling the property, this becomes even more important to understand first:
Can You Sell a Property With Undeclared Rental Income? Add once published
What You Should Do Now
If you think this may apply to you,
the most important step is not guessing your way through it.
Take the time to understand your position properly first.
👉 Book a 30-minute call here: https://calendly.com/graceca-ltd/paid-tax-property-consultation
On the call, we will look at:
- what HMRC is likely to expect
- where you currently stand
- what your next step should be
Once you understand your position and the process involved,
the next step is deciding how to move forward — and doing that with clarity makes a significant difference.