The void is a number, not a mood.

A void week is a week of headline rent you do not receive. On a £1,175.00 rent, one week is £271.15. Three weeks, which is what we allow on the Leeds terrace, is £813.46. Four weeks on the London flat is £1,615.38. The arithmetic is rent times weeks divided by 52. Write it down. A "5% void allowance" is the same idea in disguise: it is 2.6 weeks. Say the weeks, so you can argue with them.

What a week actually contains

Check-out, clean, a few repairs, photographs, viewings, referencing, and the day the new tenancy starts. A disciplined single let in a street people already want can turn in two or three weeks. Add a damp smell, a July completion when every student has already signed, or a rent set above the street, and eight weeks is ordinary. Our stress column on the Leeds house moves the void from three weeks to eight and the year stops clearing interest. The base case was never fat.

Empty weeks also attract council tax. The discount or exemption, if any, is set locally and is often short. We do not bury a heroic exemption inside the illustrations. If your council charges the full band from week five, add it. It will not rescue a thin deal, but it will stop you being surprised.

Shared houses void by the room

Illustration C does not assume the whole house is empty. It assumes one of five rooms is empty for ten weeks. That room's annual rent is £6,960.00, so ten weeks cost £1,338.46. On top we take 2% of the whole rent as arrears, £696.00, because a room can be "let" and still not pay. Voiding the whole building for ten weeks would be a different, harsher story. Using a whole-building percentage stolen from a single let is how shared-house spreadsheets lie in both directions.

Bills do not void. If you promised inclusive rent, the standing charges and the council tax continue while the room is empty. That is already inside the £6,400.00 bills line, which is why cutting the rent for a void and also cutting the bills is double counting in the landlord's favour.

Do not confuse a void with a rent cut

A void is time. A rent cut is a lower headline that you then receive. They stack. A property that takes eight weeks to let and then lets for 5% under the advert has suffered both, and the second one lasts all year. The stress page separates them so you can see which one hurts more. On a thin terrace, both are enough on their own.

There is a third cousin: a concession inside the tenancy, a month free at the start. Account for it as a void or as lower rent, once. Advertised "one month free" on a twelve-month let is an 8.3% cut if you pretend the asking rent was real. Gross yield calculators on portals almost never do this. You should.

Set the number before you fall in love with the street

Pick the weeks on the day you draft the ledger, from the last few lets on that street, not from the best story the agent tells. Then keep a worse number in the next column. If you cannot fund the worse number from salary or from other rent, you are not buying a yield. You are buying a hope that the weather stays kind.

The worksheet has a void field in weeks. The Leeds base case is three. Try eight before you decide the terrace is the sensible one.