Those six empty desks by the window are costing you the same this month as they did when they were full. Your lease does not care that two employees went remote and the contractor finished early — the rent, the CAM charges, and the insurance bill arrive in full regardless. Subletting the space you are not using is the obvious fix, and it can genuinely cut your occupancy cost in half. But here is the part most small business owners miss until something goes wrong: handing a subtenant the keys does not hand them your lease. You stay on the hook to your landlord for every dollar, every obligation, and every default — while picking up a second set of obligations to the person paying you. Get the structure right and a sublease is found money. Get it wrong and you are paying a lawyer to explain why you owe two rents at once.
Sublease vs. Assignment: The Liability Question
Start with the distinction that determines everything else, because owners routinely use the wrong word and assume the wrong outcome.
An assignment transfers your entire interest in the lease to someone else. The new tenant steps into your shoes, deals directly with the landlord, and — if the landlord agrees to a release in writing — you walk away from future liability. Landlords do not always grant that release, but assignment is at least the mechanism that can end your obligation.
A sublease creates a brand-new landlord-tenant relationship in which you are the landlord. You lease part (or all) of your space to a subtenant while your original lease — the head lease or master lease — stays fully in force between you and your landlord. The subtenant has no direct relationship with your landlord at all. That means you are on the hook to both sides at once: you owe your landlord full performance under the master lease whether or not your subtenant pays you, and you owe your subtenant quiet enjoyment of the space whether or not your landlord is cooperating.
This is not fine print. It is the entire risk profile of subletting. If your subtenant stops paying in March, your April rent to the landlord is still due in full, and a landlord who terminates the master lease over your resulting default terminates your sublease along with it — leaving you with an angry subtenant and no income to show for the trouble. Sophisticated subtenants know this, which is why experienced ones ask for a non-disturbance agreement directly from your landlord: a promise that their occupancy survives even if your lease does not. Expect the request, and do not be surprised when your landlord charges a fee or refuses outright.
The Landlord-Consent Clause That Blocks It All
Before you list the space anywhere, read your lease's assignment and subletting clause. Nearly every commercial lease requires the landlord's prior written consent before you sublease, and an unauthorized sublease is a default that can get your lease terminated — the one outcome that destroys both your tenancy and your sublease income in a single stroke.
Consent clauses come in three flavors, and yours determines how much leverage you have:
- Consent not to be unreasonably withheld. The tenant-friendly version. The landlord can still vet your proposed subtenant's finances and intended use, but cannot block the deal to extract concessions or sit on the request forever. Many states imply a reasonableness standard even when the lease is silent, but do not count on it — read the words on your page.
- Sole and absolute discretion. The landlord can say no for any reason or no reason. Common in retail and restaurant leases where tenant mix matters. If this is your clause, your sublease plan is a request, not a right.
- Deemed consent after a waiting period. Some leases say consent is deemed granted if the landlord does not respond within 15 or 30 days. Useful, but only if you send the request exactly the way the lease's notice provision requires — wrong address or wrong method, and the clock never started.
Even when consent is granted, expect strings attached. Landlords commonly reserve a profit-sharing clause (50 percent of any sublease rent above your base rent is typical), a recapture right (the landlord can take the space back instead of approving your subtenant — fine if you wanted out anyway, painful if you wanted the income), and a consent fee covering their legal review. Budget a few hundred to a few thousand dollars for that fee, and get the consent in a signed writing that names the specific subtenant, space, and term. A verbal "sure, go ahead" from a property manager is worth nothing when ownership changes or memories differ.
The Accounting: You Are Both Lessee and Lessor Now
Here is where the books get interesting. The moment you sign a sublease, you occupy two accounting roles simultaneously: you remain the lessee under the head lease, and you become the intermediate lessor (sublessor) under the sublease. Those two positions are accounted for separately — the sublease does not modify, shrink, or offset your head-lease obligation.
For businesses reporting under US GAAP, ASC 842 spells out the mechanics. You keep the head lease on your balance sheet exactly as before: the right-of-use asset and the lease liability stay put, because you were not relieved of your primary obligation. Then you classify the sublease as its own lease — and here is a nuance worth getting right: under US GAAP, an intermediate lessor classifies the sublease with reference to the underlying asset (the actual office space), not with reference to the right-of-use asset created by the head lease. (International reporters take note: IFRS 16 does the opposite. If your investor reporting crosses standards, flag the difference for your accountant.) In practice, most small-business subleases classify as operating leases, which keeps the treatment simple: you recognize sublease income, generally on a straight-line basis over the sublease term, while continuing to recognize your full head-lease cost.
The critical presentation rule applies whether or not you follow GAAP: do not net the two. Your head-lease rent and your sublease income are separate line items — cost and revenue — not a single "net rent" figure. Netting hides the true cost of your space, understates both revenue and expense, misleads anyone reading your profit and loss (lenders, buyers, partners), and makes the books useless the month the subtenant pays late. Show the full rent you owe and the full income you receive, every month, and let the reader do the subtraction.
Book Sublease Income Separately: A Practical Setup
Gross presentation is the principle; here is the practice. Set up your chart of accounts so the sublease lives in its own corner of the ledger:
- Sublease rental income as its own revenue account — never folded into your operating revenue from customers, and never netted against rent expense. If you sublease to more than one party, track each subtenant separately so a short payment is traceable in seconds.
- Rent expense continues at the full head-lease amount, exactly as before. Your obligation did not change; your books should not pretend it did.
- Pass-throughs as their own lines. Most subleases pass a share of CAM charges, utilities, insurance, or property tax to the subtenant. Book what you pay the landlord as expense and what the subtenant reimburses as income (or as a reduction recorded in a dedicated reimbursement account — consistently, either way). Crucially, preserve your right under the master lease to audit and dispute those pass-through charges, and flow any credit you win down to the subtenant proportionally. Nothing poisons a sublease faster than a CAM bill the subtenant believes — correctly — that you never questioned.
- Security deposits as liabilities, not income. A deposit you must return is not revenue when received. Hold it in a liability account, and only recognize income if a portion is legitimately forfeited or applied under the sublease terms.
- Direct costs of the sublease — broker commissions, the landlord's consent fee, legal review, any improvements you made for the subtenant — tracked against the sublease so you know whether the deal actually makes money. Amortize a large commission over the sublease term rather than expensing it all in month one if you want a meaningful monthly picture.
A quick sketch of one month makes the shape clear. Suppose your head-lease rent is $4,000, you sublease half the space for $2,200, and the subtenant reimburses $300 of CAM charges. Your books show $4,000 of rent expense (plus the full CAM expense you paid), $2,200 of sublease income, and $300 of reimbursement income. The $1,500 gap is your true remaining occupancy cost — visible, honest, and comparable month to month. The owner who nets everything to a single "$1,500 rent" line cannot see the subtenant's payment arrive late, cannot prove the income to a lender, and cannot explain the spike when the sublease ends.
The Tax Treatment Is Simpler Than the Accounting
For tax purposes, the IRS treats this the way common sense would. Sublease income is ordinary income — report all of it, generally on the same business return and schedule where you report your other business income, not on a rental schedule meant for investment property. And your head-lease rent remains fully deductible as an ordinary and necessary business expense for property you use in your business, just as it was before you took in a subtenant. You deduct what you pay; you report what you receive. The two do not cancel on the return any more than they should cancel in your ledger.
Three details catch people out. First, advance rent is income when received. If your subtenant prepays three months to secure the space, that cash is taxable in the year you receive it even though you will earn it over the following months — plan the cash and the tax bill together. Second, a security deposit is not income when received as long as it functions as a genuine deposit you must return; it becomes income only if you keep it. Third, expenses follow the business. The consent fee, broker commission, and legal costs of arranging the sublease are business expenses of generating that income — deductible, but only if you tracked them separately enough to find them at tax time. Which brings the whole article full circle: the separate bookkeeping advocated above is not just good presentation, it is the record that substantiates both the income you report and the deductions you claim.
Six Mistakes That Turn Found Money Into a Lawsuit
Most sublease disasters are not exotic. They are the same short list, repeated:
- Subletting without written consent. The landlord finds out, declares a default, and terminates the master lease. You lose your space, your subtenant sues you for the space you promised them, and the lease's attorney-fee clause means you pay for both sides of the education. Get consent first, in writing, naming the subtenant.
- No written sublease — or a handshake on key terms. At minimum, put the space, term, rent, escalation, pass-throughs, permitted use, maintenance split, insurance requirements, and default remedies in a signed document. A subtenant's "we agreed" and your "we agreed" are different documents.
- Letting the sublease run past the master lease. Your sublease term should end before your head lease does — commonly a few days to a few weeks earlier — so a holdover subtenant does not trap you into holdover rent (often 150 to 200 percent of base rent) that you owe your landlord but cannot fully pass through.
- Skipping the insurance requirement. Require the subtenant to carry commercial general liability insurance, name you as an additional insured, and deliver a certificate before move-in. Their slip-and-fall in your leased space becomes your landlord's claim against you without it.
- Ignoring the use clause. Your master lease restricts what the space may be used for, and your subtenant inherits that restriction. A quiet office lease does not cover your subtenant's podcast studio with fifty daily visitors, and the violation is yours even though the noise is theirs.
- Forgetting you are still the tenant. The landlord sends default notices, CAM reconciliations, and renewal deadlines to you, not your subtenant. Calendar every critical date from the master lease independently, and build a few days of buffer into the sublease's corresponding deadlines so a subtenant's delay never becomes your default.
One more for the road: screen a subtenant the way a landlord would screen you. Pull a credit report, verify the business exists and pays its bills, and call a prior landlord. A subtenant who cannot pay does not reduce your rent — they add a collection problem on top of it.
Keep Your Lease Ledger Audit-Ready From Day One
Subletting works when you respect what it is: a second business relationship layered on top of your first one, with its own income, its own paperwork, and its own risks — while your original obligation continues untouched. Get the landlord's written consent, keep the head lease and the sublease on visibly separate ledger lines, report every dollar of income, and calendar the master-lease dates as if the subtenant did not exist. Handled that way, those empty desks stop being a sunk cost and start being what they should have been all along: someone else's rent check arriving in your account.
That separation is straightforward double-entry work: full rent expense on one side, sublease income and pass-through reimbursements on their own lines, deposits parked as liabilities until earned. In plain-text accounting the whole arrangement lives in one version-controlled journal, reviewable without handing your data to a third-party platform, and a dashboard like Fava makes it easy to confirm the sublease income matches the bank deposits to the dollar. The setup is covered in the docs.
Turn Empty Square Footage Into Covered Rent
As you put unused space to work, maintaining clear financial records is what keeps a good sublease from becoming a confusing one. Beancount.io provides plain-text accounting that gives you complete transparency and control over your financial data — no black boxes, no vendor lock-in. Get started for free and see why developers and finance professionals are switching to plain-text accounting.
