Calculate OSR land, fee-in-lieu, and gift-deed requirements under TNCDBR Rule 41/47. Handles pre-cutoff exemption, addition-to-existing discretion, and the 2024 regularisation scheme.
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Plot area | — |
Internal roads | — |
Net land (plot − roads) | — |
OSR land carve-out 10% × net land | — |
Min parcel size for tier | — |
Fee-in-lieu base plot − 3,000 sqm exemption (or full plot for regularisation) | — |
Fee-in-lieu 10% × fee base × guideline value | — |
OSR tier applied | — |
Gift deed required | — |
Quick lookup of how OSR applies across plot sizes and special categories, per TNCDBR Rule 41/47 and GO 118/2024.
| Tier | OSR land | Fee-in-lieu | Gift deed |
|---|---|---|---|
| Pre-cutoff (Annexure XX) | Exempt | Exempt | — |
| Single building | Exempt (setbacks apply) | — | — |
| ≤ 3,000 sqm | Nil | Nil | — |
| 3,000 – 10,000 sqm | 10% × (plot − roads) | OR 10% × (plot − 3,000 sqm) × GV | No |
| ≥ 10,000 sqm | 10% × (plot − roads), mandatory | Not allowed | Yes (before sanction) |
| Industrial / institutional | 10% × (plot − roads) | Not applicable | No (owner maintains) |
| Addition to existing (≥25% built) | 10% × (plot − roads) | Discretionary | No |
| Regularisation ≤ 5,000 sqm (GO 118) | 10% × plot | OR 10% × plot × GV | No |
| Regularisation > 5,000 sqm (GO 118) | 10% × plot, mandatory | Not allowed | Per layout rules |
Min parcel size: 100 sqm (10m min dimension) for the 3k–10k tier; 500 sqm (1:5 dimension ratio) for ≥10k tier. If the carved area falls below the minimum, fee-in-lieu becomes mandatory in the 3k–10k tier; ≥10k requires DTCP/CMDA variance.
Common scenarios at GV ₹5,000/sqft with 30% internal roads (where applicable). Numbers rounded.
| Plot | Tier | OSR land (sqft) | Fee-in-lieu (₹) |
|---|---|---|---|
| 2,000 sqm layout | Below 3,000 sqm | — | — |
| 5,000 sqm layout | Land or fee | 3,767 | 1,07,63,900 |
| 8,500 sqm CMDA layout | Land or fee | 6,403 | 2,96,06,725 |
| 15,000 sqm layout | Mandatory + gift deed | 11,302 | Not allowed |
| 985 sqm regularisation (GO 118) | Cash option | 1,060 | 53,01,200 |
These are illustrative only. Actual demand notices issued by CMDA / DTCP may differ based on prevailing GV at the time of sanction and any local circulars in force.
Open Space Reservation, or OSR, is a regulatory requirement under TNCDBR 2019 (Rule 41 for buildings, Rule 47 for layouts) that obligates developers of layouts and sub-divisions to reserve a fixed percentage of total plot area as open space — parks, playgrounds, or green areas — for community use. The legal basis is Section 31 of the Tamil Nadu Town and Country Planning Act, 1971. OSR land is conveyed free of cost to the local authority through a registered gift deed (for layouts ≥ 10,000 sqm) and cannot be built upon. The rule prevents over-densification of new layouts and guarantees neighbourhood-level open space as cities expand.
Enter the total layout area, the percentage of internal roads, the planning authority, and the development category. The calculator applies four checks in order: pre-cutoff exemption (Annexure XX); single-building exemption (no OSR for building development on an existing plot); below-3,000-sqm exemption (Nil slab); and the standard tiered rule for layouts above 3,000 sqm. The land carve-out is computed as 10% of (plot area minus internal roads) — not gross plot area, since roads are excluded from the OSR base under Rule 47. The fee-in-lieu, when permitted, uses a different formula: 10% × (plot sqm − 3,000 sqm) × Guideline Value, because the first 3,000 sqm is always exempt under Annexure XX (confirmed by the Supreme Court in CMDA v. Kamala Selvaraj, 2025 INSC 1200).
The TNCDBR 2019 sets three plot-size tiers. Layouts at or below 3,000 sqm (~32,292 sq ft) are exempt from physical OSR contribution; a reservation deposit may apply but is not modelled here. Between 3,000 sqm and 10,000 sqm, the developer has a choice: reserve 10% of net layout area as OSR land, or pay a fee-in-lieu equal to 10% × (plot sqm − 3,000 sqm) × guideline value. Above 10,000 sqm, OSR land reservation is mandatory — there is no fee option, and a registered gift deed must be executed before the layout sanction is issued (Rule 47(7)). The minimum OSR parcel must be 100 sqm with a 10m minimum dimension (3k–10k tier) or 500 sqm with a 1:5 dimension ratio (≥10k tier).
Layouts and sub-divisions registered before the relevant master plan came into force fall in the "Nil" slab regardless of size. The cutoff dates are: CMDA jurisdiction = 05 August 1975 (gazette date of the First Master Plan); DTCP-Urban areas = 01 January 1980 (typical for first municipal master plans); DTCP-Rural = 29 November 1972 (T&CP Act 1971 commencement date). The Supreme Court confirmed this exemption in CMDA v. Kamala Selvaraj (2025 INSC 1200): a pre-1975 CMDA plot cannot be subjected to OSR demands even on resale or partition. Documentation typically required: pre-cutoff sale deed, partition deed, or patta. Verify the exact DTCP cutoff dates with your local DTCP office — the 1980 / 1972 dates are widely cited in practice but the underlying GO is harder to surface.
Fee-in-lieu is permitted only in the 3,000–10,000 sqm tier as an alternative to physical land reservation. The formula is 10% × (plot area in sqm − 3,000 sqm) × guideline value per sqft (after unit conversion). The "minus 3,000 sqm" piece is critical and is the most commonly mis-applied part of the rule — many calculators apply 10% × full area, which overstates the fee. Above 10,000 sqm, fee-in-lieu is not permitted at all; OSR must be land plus a registered gift deed before sanction. Below 3,000 sqm, neither land nor fee applies, though a "reservation deposit" mechanism exists in some local body schedules.
Industrial and institutional developments (factories, schools, hospitals, government buildings) follow a softer rule under Rule 41: the OSR area must still be set aside, but it is maintained by the owner under local body supervision rather than gifted to the authority. No registered gift deed is required, and the land remains with the owner subject to use restrictions. Additions to an existing development — defined as where existing structures already cover 25% or more of the total plot area at the time of new building permit application — qualify for executive authority discretion: the planning officer may accept a fee-in-lieu instead of forcing a fresh OSR carve-out, on the reasoning that physical reservation is impractical on a partly-built site. The 25% threshold is from the older CMDA Development Control Regulations and survived into how planning officers apply Rule 41 today.
The 2024 amendment to the Tamil Nadu Regularisation of Unapproved Layouts and Plots Rules 2017 (notified through GO 118 of the Housing & Urban Development Department) created a separate code path for unapproved layouts being regularised. For layouts with unsold plot area up to 5,000 sqm, the developer may choose between reserving 10% of the unsold plot area as OSR or paying 10% of the guideline value of the unsold plot area in cash. This 5,000 sqm cash-option rule applies only to the regularisation scheme — it does NOT apply to fresh layout approvals under TNCDBR 2019. The deadline for regularisation applications under this scheme was extended to 29 February 2024. If your project is a fresh layout, ignore this category; if your project is a 2017-Rules regularisation, use this category and the calculator will apply the cash-option formula.
Rule 41 of TNCDBR explicitly permits a small number of structures on OSR land, capped at 5% of the total OSR area in one place: a watchman’s booth, gardener’s instrument room, public toilet, and police booth. Below ground, the OSR land may host public parking, rainwater harvesting tanks, and sewage treatment plants. Anything beyond these uses requires a planning authority NOC and is normally not permitted. The OSR land continues to receive proportionate FSI benefit on the parent plot — that is, the OSR area is excluded from FSI computation for the OSR carve-out itself but the parent plot’s FSI calculation includes its share.
Non-compliance with OSR rules attracts penalties under the Tamil Nadu Town and Country Planning Act, 1971: Section 47 mandates planning permission, Section 48 governs sanction conditions, Section 56 empowers the authority to require removal of unauthorised development, Section 85 provides for restoration to original state where development contravenes Sections 47/48, and Section 86 is the criminal-fine provision. In practice, planning officers issue demand notices for unpaid fee-in-lieu charges with interest typically calculated at 12% per annum — note that the 12% rate is administrative (set in fee-collection GOs) rather than statutory and is subject to revision; do not rely on this calculator’s output for litigation purposes without verifying the prevailing rate with the local CMDA / DTCP office.
OSR directly reduces the saleable area of a layout and, when fee-in-lieu is paid, directly impacts cash flow. On a 1-acre (4,047 sqm) layout, 10% OSR on net land removes ~283 sqm (~3,047 sq ft) of saleable land — at typical Chennai-suburb plot rates, that is ₹40–80 lakhs of foregone revenue. Above 10,000 sqm, the gift-deed-before-sanction requirement adds 30–60 days of legal lead time. Layouts that miss OSR planning at the feasibility stage end up with awkward leftover plots, missed gift-deed timelines, or unexpected fee-in-lieu cash demands. Run this calculator before you finalise a layout acquisition.
This is a v1 calculator. It does not model: the additional 1% public-purpose carve-out (0.5% to local body + 0.5% to TANGEDCO under Rule 47); EWS plot reservation requirements for large subdivisions (Rule 47(8–12)); joint development cases where OSR liability is split contractually; redevelopment of existing OSR-bearing layouts (gift deeds already executed cannot be reversed); layouts straddling CMDA / DTCP boundary lines (each jurisdiction’s rule applies pro-rata); and SIPCOT / TIDCO industrial estate norms. The "what if the local body refuses to accept the OSR" operational risk is not modelled because there is no statutory remedy — flag it as a process risk in your acquisition workflow.
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