Net effective rent (NER) is the average rent a landlord actually collects after concessions, spread evenly across the lease term. The simplest formula is (total gross rent over the lease term − total landlord concessions) ÷ number of lease periods. That gives you a single comparable rate per month or year. A discounted version exists for institutional deals, and worked examples below show exactly how the numbers move.
TL;DR:
- Discounted net effective rent can significantly alter the perceived cost of long-term commercial leases with upfront tenant improvements and free rent periods.
- Proper unit consistency, including aligning months with years and area measurements, is essential to avoid calculation errors.
- Adding costs like outgoings and escalations is crucial for an accurate total occupancy cost comparison beyond NER alone.
- Mistakes such as omitting leasing commissions or misapplying concession timing can lead to overstated or understated rent assessments.
- Using a simple spreadsheet template helps ensure consistent calculations, but verifying lease details and concessions remains critical for reliable results.
Table of Contents
- What is net effective rent and how do you calculate it?
- When should you use a discounted NER formula?
- Two worked examples of effective rent calculation
- Why NER alone doesn’t tell you the total occupancy cost
- What mistakes wreck an effective rent calculation?
- How do you build a quick NER calculator template?
- Where to go from here with your effective rent numbers
- Sources
What is net effective rent and how do you calculate it?
Net effective rent strips away the marketing gloss on a lease. It’s the average rent paid over the term after subtracting every concession the landlord threw in to win the deal. Face rent (also called gross or headline rent) is the number on the lease document. NER is what the deal actually costs once you account for the sweeteners.
Concessions typically include:
- Free rent periods (one to several months paying nothing)
- Tenant improvement (TI) allowances, cash or credit for fit out
- Leasing commissions the landlord absorbs on the tenant’s behalf
- Reduced rent steps or holdover waivers written into early years
The core formula scales depending on what you need:
- Monthly NER = (Gross rent × months actually paid − concession value) ÷ total lease months
- Annual NER = Monthly NER × 12
- NER per square metre or per square foot = Annual NER ÷ leased area
Denominator choice matters more than most people realise. Mixing months into a formula that expects years, or dividing by leased area in square feet when your rent is quoted per square metre, produces a number that looks plausible and is completely wrong. Keep every input in the same unit before you divide anything.
When should you use a discounted NER formula?
Simple NER treats every dollar the same, whether it lands in month one or month thirty six. That’s fine for a twelve-month residential lease. It breaks down for a ten-year commercial deal where the landlord hands over a six-figure TI cheque upfront and free rent sits at the front of the term.
Discounted NER fixes this by applying the time value of money:
- Discounted NER = (sum of CFt ÷ (1+r)^t for each period) ÷ n, where CFt is the net cash flow in period t and r is your discount rate
- Treat the TI allowance as a negative cash flow at time zero, not spread evenly across the term
- Free months become zero-rent periods in the cash flow sequence, not a lump subtracted at the end
Picking the discount rate is where judgement comes in. It should reflect the tenant’s cost of capital or unsecured borrowing rate, since that’s the real cost of forgoing cash now versus later. Industry underwriting on longer commercial deals commonly uses discount rates around 8.2% to reflect that risk and timing.
Rule of thumb: for short residential leases, simple NER is close enough. For anything over five years with a large upfront TI, the discounted version can shift your effective cost by a meaningful margin.
Two worked examples of effective rent calculation
Residential example: one free month on a 12-month lease
- Face rent is $2,500 a month. The landlord offers one month free to sign.
- Total gross rent over 12 months at face value would be $30,000.
- The tenant actually pays for 11 months: 11 × $2,500 = $27,500.
- Monthly NER = $27,500 ÷ 12 = a value roughly 8% below face rent.
- That’s an 8.3% discount to face rent, purely from the free month.
Commercial example: face rate, free months and a TI allowance
- Face rent is $600 per square metre annually, on a 5 year (60 month) lease over 500 sqm.
- The landlord offers 3 months free and a TI allowance of $80 per square metre.
- Total face rent over the term = $600 × 500 × 5 = $1,500,000.
- Concession value: 3 months free = $600 × 500 ÷ 12 × 3 = $75,000. TI allowance = $80 × 500 = $40,000. Total concessions = $115,000.
- NER over the term = ($1,500,000 − $115,000) ÷ 5 years = $277,000 a year.
- NER per square metre = $277,000 ÷ 500 = a value roughly 7.7% below the $600 face rate, a roughly 7.7% reduction against the $600 face rate.
The mechanics are identical to the smaller residential figure. Bigger numbers, same arithmetic, same traps if you mix up months and years anywhere in the sequence.
Why NER alone doesn’t tell you the total occupancy cost
NER measures rent. It says nothing about the other charges layered on top, and on commercial leases those charges often move the needle further than the NER gap between two offers.
Add these to get a true comparison:
- Net, net, net (NNN) or outgoings: council rates, land tax, building insurance, land tax
- Common area maintenance (CAM): cleaning, security, lift maintenance, shared services
- Annual escalations on both rent and outgoings, typically 3 to 5% a year
Watch for CAM caps, contractual ceilings on how much the landlord can pass through each year, and exclusions that quietly shift costs back onto the tenant. Two offers with nearly identical NER can land thousands apart once outgoings are projected across the full term.
Pro Tip: Build a simple annual total occupancy cost line: NER per sqm plus estimated NNN per sqm, escalated at the rate specified in the lease. Compare that number across offers, not the NER alone.
What mistakes wreck an effective rent calculation?
The arithmetic is simple. The inputs are where deals go wrong.
- Mixing bases: dividing an annual concession figure by monthly periods, or vice versa
- Using the wrong denominator: total lease months when the concession only ran for part of the term
- Omitting leasing commissions or TI from the concession total because they weren’t paid “in cash”
- Confusing advertised (asking) rent with the actual contract rent signed
- Treating a TI allowance as spread evenly when it was really a lump sum paid upfront
Before you finalise a comparison, run through this checklist:
- Confirm the exact lease term, including any option periods
- Confirm where free months sit in the schedule, front loaded or back loaded
- Confirm whether TI is cash paid to the tenant or amortised into the rent schedule
- Confirm every commission the landlord absorbed on your behalf
- Confirm escalation clauses and whether they apply to rent, outgoings, or both
Non-financial clauses matter too. Renewal options, exclusivity and make-good obligations can outweigh a small NER gap, so don’t let the spreadsheet make the whole decision. If a landlord won’t provide a clean breakdown of concessions, that’s a signal to ask a tenant adviser to model it properly.
How do you build a quick NER calculator template?
A basic spreadsheet needs only a handful of labelled cells:
- A = Gross monthly rent
- B = Total lease months
- C = Free months
- D = Total TI allowance ($)
- Monthly NER = (A × (B − C) − D) ÷ B
- Annual NER = Monthly NER × 12
- NER per sqm = Annual NER ÷ leased area (sqm)
For the discounted version, add a column for each period’s net cash flow, apply =CFt/(1+r)^t against your chosen discount rate, sum the results, then divide by the number of periods. Put TI as a negative cash flow at t = 0 and free months as zero in the relevant row.
Double check units before you trust any output. Sqm versus square feet, and months versus years, are the two mismatches that silently break this template.
Where to go from here with your effective rent numbers
Simple NER is enough for short residential leases and straightforward comparisons. Once you’re looking at a multi-year commercial lease with a large TI allowance, front-loaded free rent, or escalating outgoings, the discounted version and a total occupancy cost comparison earn their keep.
Run the template above on every offer, add projected NNN, and verify every input against the actual lease document, not the marketing flyer. For a lease that’s material to your business, a modelling error costs far more than the time it takes to get it checked. Niche Advisory works with tenants on exactly this kind of analysis, and if the numbers are getting complicated, speaking with a tenant adviser before you sign is cheaper than fixing it after.
Sources
- Net Effective Rent | Formula + Calculator — Wall Street Prep
- Realestate
- Net effective rent — Wikipedia
