Seven free calculators for the landlord questions that are easiest to get wrong

There are now seven free calculators at tenarize.com/tools. They take no account, no email address and no card, they answer the question completely on the page, and five of the seven run the same statutory logic the Tenarize product runs — from a copy of the same code, checked automatically so the two cannot drift apart.

They exist because of a pattern in the questions landlords actually ask. Almost none of them are about the law in general. They are about a number: is this notice long enough, have I still got time, when does this certificate run out, how much may I take, what am I allowed to charge. And a number is the part of a legal duty where being nearly right is the same as being wrong.

The problem with these particular dates

Four duties, four ways the arithmetic goes wrong quietly.

Notice periods are not one number. A Section 8 notice can require anything from two weeks to four months depending on which ground you cite, and where you cite several, the longest one binds the whole notice. A landlord who cites serious arrears alongside a ground for moving back in has given a four-month notice, whatever they wrote on it.

The deposit clock starts a day earlier than people count it. The deposit protection duties run "within the period of 30 days beginning with" the day the deposit is received. "Beginning with" makes the day of receipt day one, so the last lawful day is the date of receipt plus twenty-nine. Count from the following morning, as almost everyone does, and you have given yourself a deadline one day after the real one.

A certificate interval is not always the interval. An EICR lasts at most five years — but if the report itself specifies an earlier retest date, that earlier date is the one that binds. And Legionella risk assessments have no statutory interval at all, so any tool that hands you an anniversary for one has invented a legal deadline.

Landlord registration has a rumour problem. The Private Rented Sector Database now has official dates, deadlines and a fee, and a penalty figure circulating beside them that does not come from the government.

What being a day out actually costs

None of these are duties where the cost scales with how wrong you were.

A notice that is too short does not get shortened by the court or held over until it ripens. The possession claim is refused, and the period starts again from the day you serve a corrected one — so a fortnight's miscalculation costs the whole notice period plus however long it took to find out.

A deposit protected on day thirty-one is not slightly late. It is a breach, and it stays a breach after you fix it: the tenant's ability to apply to the court survives you eventually complying. Both halves of that duty carry it independently, which is the part that catches people — putting the money in a scheme and never sending the prescribed information is a complete failure of the duty, not half of one.

A lapsed gas safety certificate is a criminal matter rather than an administrative one, and the gap between "I renewed it in the spring" and "I renewed it fourteen months ago" is invisible until somebody asks.

And the certificates are about to become considerably harder to be vague about, because landlord registration will ask you to upload them with their dates.

The common shape: you do not find out you were wrong at the moment you were wrong. You find out at the moment it matters, which is the worst possible moment to be starting a four-month clock.

The seven tools

Section 8 notice period

Pick the grounds you are citing and the date you are serving, and it shows the earliest date each ground allows a notice to expire — and which of them is setting the deadline for the whole notice. Sixteen grounds, with their statutory minimums: four months, two months, four weeks or two weeks depending on the ground, and none at all for grounds 7A and 14.

What it will not do is tell you whether a ground applies to your situation, or that your notice is valid. Choosing the ground is yours, and a notice can be exactly the right length and still fail on the form, the service or what was outstanding at the time.

Deposit protection deadline

Enter the date the deposit reached you and it gives you the last lawful day for both duties — the money into an authorised scheme, and the prescribed information to the tenant. It counts the way the statute counts, which is the whole reason the page exists.

It gives you a date. It cannot know whether the money actually arrived at a scheme, or whether what you sent your tenant was the prescribed information rather than a covering email.

Certificate expiry date

Pick a certificate and its issue date and it gives you the expiry, plus the date to have the next visit booked by. It carries the rules that trip people up rather than smoothing them over: a gas check carried out in the two months before expiry keeps the original anniversary, so booking early does not shorten your next cycle — a genuinely useful rule that a lot of landlords have never been told. The EPC runs ten years. The EICR runs five at most, with the report's own retest date overriding it.

Legionella and fire risk assessments deliberately get no date, because the law sets none.

Landlord database registration

Whether the new register applies to a property, and when registration opens and closes where it is. Pick your region from the nine the draft regulations name and it gives you both dates from the government's own table: the West Midlands opens on 15 December 2026 with a deadline of 14 March 2027, and the South West, last, has until 14 November 2027.

It is careful about two things, and they are what make it worth a page. The regulations behind those dates are still in draft, and the tool says so once, plainly, rather than presenting them as law already made. And it separates what the government has published from what is merely circulating: the £65 annual fee per property is the government's figure and the tool states it, while the penalty figure quoted widely is not, and the tool says that too.

Deposit cap

Enter the rent and it gives you the most you may lawfully take: five weeks' rent, or six where the annual rent is £50,000 or more, under the Tenant Fees Act 2019. Enter the deposit you have taken as well and it says whether that figure sits under the cap.

The arithmetic is the reason it exists. A week's rent is the annual rent divided by 52, whatever the rent is actually paid — so five weeks is the monthly rent multiplied by about 1.15, not by 1.25. A month is 4.33 weeks rather than four, and reasoning in months overstates the cap by roughly 8%. On a £1,200 rent that is £115 too much, and it is the excess rather than the intention that makes it a prohibited payment.

It gives the holding deposit cap alongside it — one week's rent, a separate payment with its own limit — and it says plainly what being under the cap does not do, which is discharge either of the protection duties.

Late rent interest

What may be charged when the rent is late, and what has accrued so far. Two limits do most of the work: nothing at all may be charged until the rent is more than fourteen days overdue, and the rate may not exceed the Bank of England base rate plus three percentage points. Interest within that ceiling is the only permitted charge — a flat late fee, an administration charge or a letter fee is a prohibited payment whatever the tenancy agreement calls it.

This is the only calculator on the site whose answer moves without anybody editing our code, because the Monetary Policy Committee can change Bank Rate eight times a year. So the page fetches the rate rather than printing it, tells you which rate it used and when that rate was read, and says so plainly on the occasions it cannot confirm today's. A page stating last year's cap would be telling a landlord they may charge a tenant more than the law allows.

HMO licence

Whether mandatory HMO licensing applies: five or more people, in two or more households, sharing a toilet, bathroom or kitchen. The checker asks for the people and the households separately, because that is where this gets miscounted. A family of four plus one lodger is five people in two households and is licensable. A couple with three children is five people in one household and is not an HMO at all.

It also retires a rule a great deal of advice still repeats: the three-storey condition went when the Licensing of Houses in Multiple Occupation (Prescribed Description) (England) Order 2018 revoked the 2006 order, with effect from 1 October 2018. A bungalow can need a mandatory licence.

What it will never do is tell you that you do not need a licence. Additional and selective licensing are designated council by council, and selective licensing covers ordinary single lets — so every answer short of "yes" ends at GOV.UK's postcode lookup rather than at a conclusion.

What they cannot tell you, in writing

Every one of the seven carries a limits section, and those sections are not small print bolted on at the end. They are the reason the rest of the page is worth reading.

A tool that computes a legal date and does not say what it cannot see is inviting you to trust it further than it has earned. So each page says outright: it does arithmetic on dates you type in, it does not advise, and having an in-date certificate is not the same thing as being compliant — the gas check still has to have been done by a Gas Safe registered engineer, the EICR's remedial work still has to have been carried out, and the tenant still has to have been given a copy.

Each page also carries the date its rules were last read at source, and names the document somebody has to re-read to move that date. A page that computes a statutory deadline and will not say when it was last checked is asking for a kind of trust it has not done the work for.

Where these came from

Five of them are not reimplementations of what Tenarize does. They run copies of the product's own modules — the Section 8 grounds table, the deposit deadline logic, the certificate intervals, the deposit caps and the late-payment interest arithmetic — and a check in our build fails if a copy drifts from the original.

That matters more than it sounds. Two different answers to "is this notice long enough", one on a public page and one inside the product, would be worse than either being wrong on its own. So a landlord working out a notice period at tenarize.com/tools and a landlord reading a warning inside Tenarize are being told the same thing by the same code.

Two of them are exceptions, and both are worth naming. The landlord database checker has no product feature behind it because there is no register to integrate with yet; it runs against GOV.UK's announcement and the draft regulations, and nothing else. The HMO checker answers a question Tenarize has never decided for anybody: the product tracks a licence and its expiry date, it does not hold a view on whether one is required, because that turns on who lives there and on what a particular council has designated.

Neither carries a drift check, and we would not claim they do — on either page, the closing note says what the product actually does instead.

What this changes

The everyday version of these duties is not dramatic. It is a landlord with a deposit in their account on a Tuesday, a certificate somewhere in an email thread, a fifth person moving into a house share, and a rough sense that there is time. The calculators turn each of those into a figure on a screen in about fifteen seconds, which is roughly fifteen seconds less than it takes to decide to look it up properly later.

If you want the dates to arrive rather than be looked up, that is the product: expiry reminders before a certificate lapses rather than after, the deposit deadline tracked from the date the money was actually received and recorded as done on time or done late rather than folded into one tick, and Section 8 grounds with the earliest valid expiry worked out from the ones you cite and a warning naming the ground if you set it shorter. Tenarize warns and saves anyway, because the same field records a tenant's notice to quit and a court order — it does not decide for you whether your notice is good.

But the calculators are free, they are complete, and there is nothing to sign up to. If all you needed was the number, take the number.

Where to check this yourself

• Repossessing your privately rented property after 1 May 2026 — GOV.UK, and the grounds for possession guidance
• Deposit protection schemes and landlords — GOV.UK, including the three approved schemes
• Landlords' responsibility for gas safety — HSE, with the Gas Safe Register
• Electrical safety standards in the private rented sector — GOV.UK, the EICR guidance
• Minimum energy efficiency standard: landlord guidance and find an energy certificate — GOV.UK
• Legionella: landlords' responsibilities — HSE
• Implementing the Renters' Rights Act 2025: our roadmap — GOV.UK, for the database and the ombudsman
• Tenant Fees Act 2019 — legislation.gov.uk, the deposit caps and what may be charged for late rent
• House in multiple occupation licence — GOV.UK, by postcode, because your own council sets the threshold
• Shelter and Citizens Advice — free, independent advice on a specific situation

All seven calculators are at tenarize.com/tools, free and without an account. If you want the dates tracked for you rather than calculated one at a time, Tenarize is £15 a month for one to five properties and the first month is free. The help centre is free to read either way.