Most seasoned accountants will remember using the indexation method to calculate capital gain tax (CGT), back in the day.  

Many of us were unhappy with the switch to the 50% discount method on 1 October 1999, believing that our clients would be worse off.  

Now that we’re switching back to the indexation method we originally had, the same disgruntled sentiments are rising. Which may go to show, change is the real challenge.

Happily, we can use mathematics as a means to test the validity of those sentiments. So, we conducted an analysis to compare taxpayer outcomes when using the different systems for calculating CGT. Would our clients be better off or worse off? We also wanted to study the difference between an individual owning property versus a company owning it. For the purposes of this study, our model makes the following assumptions:

  • We ignore the small business CGT discounts.
  • The individual taxpayer is already in the top marginal tax bracket.
  • If a company owns the property, an individual owns the shares in the company and receives the proceeds from the sale as a dividend, resulting in the individual paying tax at 47%. This allows us to compare individual and company ownership on an equivalent basis.

CGT calculations

Calculating CGT under the discount method is straightforward: work out the gain by subtracting the original cost from the selling price, then halve the result if the owner held the property for more than 12 months.  

The indexation method is different, as the cost base of the property moves up or down with inflation. Under indexation, we calculate the gain by taking the selling price and subtracting the cost, adjusted for inflation.

CGT calculation method 

Formula: Capital gain = 

Discount method 

50% x (Selling price - Original cost) 

Indexation method 

Selling price - Original cost x CPI factor 

Each of the scenarios below shows the tax that individual A would pay over a 20-year period under both the indexed method and the discounting method. The last two columns show the amount of tax payable where an individual owns shares in a company which makes a capital gain, and pays that gain to the individual as a dividend, with the individual paying tax at 47%

Base scenario assumptions:

  • The property is held for at least 12 months.
  • The CPI factor = (1 + inflation rate %).
  • For the indexation formula, where the selling price is less than the (original cost x CPI factor), no capital gains arise.
  • Initial property cost in 2027: $1m 

Property 

New CGT method (indexed) 

Old 50% CGT discount 

Company CGT 

Year of 
sale 

Property sale price 

Property 
indexed cost 

Gain on 
sale A 

A's tax @ 
47% 

Gain on 
sale 

Less 50% 
discount 

Taxable 
gain 

A's tax @ 
47% 

Gain for 
company 

Tax for A @ 
47% 

2028 

1,030,000 

1,030,000 

0 

0- 

30,000 

(15,000) 

15,000 

7,050 

30,000 

14,100 

2029 

1,060,900 

1,060,900 

0 

0- 

60,900 

(30,450) 

30,450 

14,312 

60,900 

28,623 

2030 

1,092,727 

1,092,727 

0 

0- 

92,727 

(46,364) 

46,364 

21,791 

92,727 

43,582 

2031 

1,125,509 

1,125,509 

0 

0- 

125,509 

(62,754) 

62,754 

29,495 

125,509 

58,989 

2032 

1,159,274 

1,159,274 

0 

0- 

159,274 

(79,637) 

79,637 

37,429 

159,274 

74,859 

2033 

1,194,052 

1,194,052 

0 

0- 

194,052 

(97,026) 

97,026 

45,602 

194,052 

91,205 

2034 

1,229,874 

1,229,874 

0 

0- 

229,874 

(114,937) 

114,937 

54,020 

229,874 

108,041 

2035 

1,266,770 

1,266,770 

0 

0- 

266,770 

(133,385) 

133,385 

62,691 

266,770 

125,382 

2036 

1,304,773 

1,304,773 

0- 

0- 

304,773 

(152,387) 

152,387 

71,622 

304,773 

143,243 

2037 

1,343,916 

1,343,916 

0- 

0- 

343,916 

(171,958) 

171,958 

80,820 

343,916 

161,641 

2038 

1,384,234 

1,384,234 

0- 

0- 

384,234 

(192,117) 

192,117 

90,295 

384,234 

180,590 

2039 

1,425,761 

1,425,761 

0- 

0- 

425,761 

(212,880) 

212,880 

100,054 

425,761 

200,108 

2040 

1,468,534 

1,468,534 

0- 

0- 

468,534 

(234,267) 

234,267 

110,105 

468,534 

220,211 

2041 

1,512,590 

1,512,590 

0- 

0- 

512,590 

(256,295) 

256,295 

120,459 

512,590 

240,917 

2042 

1,557,967 

1,557,967 

0- 

0- 

557,967 

(278,984) 

278,984 

131,122 

557,967 

262,245 

2043 

1,604,706 

1,604,706 

0 

0- 

604,706 

(302,353) 

302,353 

142,106 

604,706 

284,212 

2044 

1,652,848 

1,652,848 

0- 

0- 

652,848 

(326,424) 

326,424 

153,419 

652,848 

306,838 

2045 

1,702,433 

1,702,433 

0- 

0- 

702,433 

(351,217) 

351,217 

165,072 

702,433 

330,144 

2046 

1,753,506 

1,753,506 

0- 

0- 

753,506 

(376,753) 

376,753 

177,074 

753,506 

354,148 

2047 

1,806,111 

1,806,111 

0- 

0- 

806,111 

(403,056) 

403,056 

189,436 

806,111 

378,872 

Scenario one: 3% inflation, 3% property value increase

This table assumes inflation runs at 3% and the property price increases at the same 3% rate each year. Under indexation, the gain is nil. Under the discount method a gain arises because the selling price exceeds the original cost of the property  

In this scenario, owning the property through a company results in the highest tax bill.

Property 

New CGT method 

Old 50% CGT discount 

Company CGT 

Year of 
sale 

Property sale price 

Property 
indexed cost 

Gain on 
sale A 

A's tax @ 
47% 

Gain on 
sale 

Less 50% 
discount 

Taxable 
gain 

A's tax @ 
47% 

Gain for 
company 

Tax for A @ 
47% 

2028 

1,050,000 

1,030,000 

20,000 

9,400 

50,000 

(25,000) 

25,000 

11,750 

50,000 

23,500 

2029 

1,102,500 

1,060,900 

41,600 

19,552 

102,500 

(51,250) 

51,250 

24,088 

102,500 

48,175 

2030 

1,157,625 

1,092,727 

64,898 

30,502 

157,625 

(78,813) 

78,813 

37,042 

157,625 

74,084 

2031 

1,215,506 

1,125,509 

89,997 

42,299 

215,506 

(107,753) 

107,753 

50,644 

215,506 

101,288 

2032 

1,276,282 

1,159,274 

117,007 

54,994 

276,282 

(138,141) 

138,141 

64,926 

276,282 

129,852 

2033 

1,340,096 

1,194,052 

146,043 

68,640 

340,096 

(170,048) 

170,048 

79,922 

340,096 

159,845 

2034 

1,407,100 

1,229,874 

177,227 

83,296 

407,100 

(203,550) 

203,550 

95,669 

407,100 

191,337 

2035 

1,477,455 

1,266,770 

210,685 

99,022 

477,455 

(238,728) 

238,728 

112,202 

477,455 

224,404 

2036 

1,551,328 

1,304,773 

246,555 

115,881 

551,328 

(275,664) 

275,664 

129,562 

551,328 

259,124 

2037 

1,628,895 

1,343,916 

284,978 

133,940 

628,895 

(314,447) 

314,447 

147,790 

628,895 

295,580 

2038 

1,710,339 

1,384,234 

326,105 

153,270 

710,339 

(355,170) 

355,170 

166,930 

710,339 

333,859 

2039 

1,795,856 

1,425,761 

370,095 

173,945 

795,856 

(397,928) 

397,928 

187,026 

795,856 

374,052 

2040 

1,885,649 

1,468,534 

417,115 

196,044 

885,649 

(442,825) 

442,825 

208,128 

885,649 

416,255 

2041 

1,979,932 

1,512,590 

467,342 

219,651 

979,932 

(489,966) 

489,966 

230,284 

979,932 

460,568 

2042 

2,078,928 

1,557,967 

520,961 

244,852 

1,078,928 

(539,464) 

539,464 

253,548 

1,078,928 

507,096 

2043 

2,182,875 

1,604,706 

578,168 

271,739 

1,182,875 

(591,437) 

591,437 

277,976 

1,182,875 

555,951 

2044 

2,292,018 

1,652,848 

639,171 

300,410 

1,292,018 

(646,009) 

646,009 

303,624 

1,292,018 

607,249 

2045 

2,406,619 

1,702,433 

704,186 

330,968 

1,406,619 

(703,310) 

703,310 

330,556 

1,406,619 

661,111 

2046 

2,526,950 

1,753,506 

773,444 

363,519 

1,526,950 

(763,475) 

763,475 

358,833 

1,526,950 

717,667 

2047 

2,653,298 

1,806,111 

847,186 

398,178 

1,653,298 

(826,649) 

826,649 

388,525 

1,653,298 

777,050 

 The lower tax outcome method is highlighted in green, followed by amber and red. 

Scenario two: 3% inflation, 5% property price increase

So what happens if we assume indexation runs at 3% and property prices increase at 5% pa? In this scenario, taxpayer A is better off under indexation for the next 17 years compared with the discount method. Thereafter, the discounted CGT method results in a lower tax amount payable. Again, the company owning the property results in higher tax. 

Property 

New CGT method 

Old CGT discounting method 

Company CGT 

Year of 
sale 

Property sale price 

Property 
indexed cost 

Gain on 
sale A 

A's tax @ 
47% 

Gain on 
sale 

Less 50% 
discount 

Taxable 
gain 

A's tax @ 
47% 

Gain for 
company 

Tax for A @ 
47% 

2028 

1,030,000 

1,050,000 

(20,000) 

0- 

30,000 

(15,000) 

15,000 

7,050 

30,000 

14,100 

2029 

1,060,900 

1,102,500 

(41,600) 

0- 

60,900 

(30,450) 

30,450 

14,312 

60,900 

28,623 

2030 

1,092,727 

1,157,625 

(64,898) 

0- 

92,727 

(46,364) 

46,364 

21,791 

92,727 

43,582 

2031 

1,125,509 

1,215,506 

(89,997) 

0- 

125,509 

(62,754) 

62,754 

29,495 

125,509 

58,989 

2032 

1,159,274 

1,276,282 

(117,007) 

0- 

159,274 

(79,637) 

79,637 

37,429 

159,274 

74,859 

2033 

1,194,052 

1,340,096 

(146,043) 

0- 

194,052 

(97,026) 

97,026 

45,602 

194,052 

91,205 

2034 

1,229,874 

1,407,100 

(177,227) 

0- 

229,874 

(114,937) 

114,937 

54,020 

229,874 

108,041 

2035 

1,266,770 

1,477,455 

(210,685) 

0- 

266,770 

(133,385) 

133,385 

62,691 

266,770 

125,382 

2036 

1,304,773 

1,551,328 

(246,555) 

0- 

304,773 

(152,387) 

152,387 

71,622 

304,773 

143,243 

2037 

1,343,916 

1,628,895 

(284,978) 

0- 

343,916 

(171,958) 

171,958 

80,820 

343,916 

161,641 

2038 

1,384,234 

1,710,339 

(326,105) 

0- 

384,234 

(192,117) 

192,117 

90,295 

384,234 

180,590 

2039 

1,425,761 

1,795,856 

(370,095) 

0- 

425,761 

(212,880) 

212,880 

100,054 

425,761 

200,108 

2040 

1,468,534 

1,885,649 

(417,115) 

0- 

468,534 

(234,267) 

234,267 

110,105 

468,534 

220,211 

2041 

1,512,590 

1,979,932 

(467,342) 

0- 

512,590 

(256,295) 

256,295 

120,459 

512,590 

240,917 

2042 

1,557,967 

2,078,928 

(520,961) 

0- 

557,967 

(278,984) 

278,984 

131,122 

557,967 

262,245 

2043 

1,604,706 

2,182,875 

(578,168) 

0- 

604,706 

(302,353) 

302,353 

142,106 

604,706 

284,212 

2044 

1,652,848 

2,292,018 

(639,171) 

0- 

652,848 

(326,424) 

326,424 

153,419 

652,848 

306,838 

2045 

1,702,433 

2,406,619 

(704,186) 

0- 

702,433 

(351,217) 

351,217 

165,072 

702,433 

330,144 

2046 

1,753,506 

2,526,950 

(773,444) 

0- 

753,506 

(376,753) 

376,753 

177,074 

753,506 

354,148 

2047 

1,806,111 

2,653,298 

(847,186) 

0- 

806,111 

(403,056) 

403,056 

189,436 

806,111 

378,872 

Scenario three: 5% inflation, 3% property price increase

Assuming inflation runs at 5% and the property increases at 3%. As before, indexation yields the lowest tax bill and creates a capital loss. The discount method results in tax payable because the property has gone up in value, even though the real value of money has not. This shows that under the discounting method, whilst people make a gain, the gain after adjusting for inflation may not even exist, and substantial tax is paid on something which may not even be real. 

Property 

New CGT method 

Old CGT discounting method 

Company CGT 

Year of 
sale 

Property sale price 

Property 
indexed cost 

Gain on 
sale A 

A's tax @ 
47% 

Gain on 
sale 

Less 50% 
discount 

Taxable 
gain 

A's tax @ 
47% 

Gain for 
company 

Tax for A @ 
47% 

2028 

1,030,000 

1,050,000 

(20,000) 

0- 

30,000 

(15,000) 

15,000 

7,050 

30,000 

14,100 

2029 

1,060,900 

1,102,500 

(41,600) 

0- 

60,900 

(30,450) 

30,450 

14,312 

60,900 

28,623 

2030 

1,092,727 

1,157,625 

(64,898) 

0- 

92,727 

(46,364) 

46,364 

21,791 

92,727 

43,582 

2031 

1,125,509 

1,215,506 

(89,997) 

0- 

125,509 

(62,754) 

62,754 

29,495 

125,509 

58,989 

2032 

1,159,274 

1,276,282 

(117,007) 

0- 

159,274 

(79,637) 

79,637 

37,429 

159,274 

74,859 

2033 

1,194,052 

1,340,096 

(146,043) 

0- 

194,052 

(97,026) 

97,026 

45,602 

194,052 

91,205 

2034 

1,229,874 

1,407,100 

(177,227) 

0- 

229,874 

(114,937) 

114,937 

54,020 

229,874 

108,041 

2035 

1,266,770 

1,477,455 

(210,685) 

0- 

266,770 

(133,385) 

133,385 

62,691 

266,770 

125,382 

2036 

1,304,773 

1,551,328 

(246,555) 

0- 

304,773 

(152,387) 

152,387 

71,622 

304,773 

143,243 

2037 

1,343,916 

1,628,895 

(284,978) 

0- 

343,916 

(171,958) 

171,958 

80,820 

343,916 

161,641 

2038 

1,384,234 

1,710,339 

(326,105) 

0- 

384,234 

(192,117) 

192,117 

90,295 

384,234 

180,590 

2039 

1,425,761 

1,795,856 

(370,095) 

0- 

425,761 

(212,880) 

212,880 

100,054 

425,761 

200,108 

2040 

1,468,534 

1,885,649 

(417,115) 

0- 

468,534 

(234,267) 

234,267 

110,105 

468,534 

220,211 

2041 

1,512,590 

1,979,932 

(467,342) 

0- 

512,590 

(256,295) 

256,295 

120,459 

512,590 

240,917 

2042 

1,557,967 

2,078,928 

(520,961) 

0- 

557,967 

(278,984) 

278,984 

131,122 

557,967 

262,245 

2043 

1,604,706 

2,182,875 

(578,168) 

0- 

604,706 

(302,353) 

302,353 

142,106 

604,706 

284,212 

2044 

1,652,848 

2,292,018 

(639,171) 

0- 

652,848 

(326,424) 

326,424 

153,419 

652,848 

306,838 

2045 

1,702,433 

2,406,619 

(704,186) 

0- 

702,433 

(351,217) 

351,217 

165,072 

702,433 

330,144 

2046 

1,753,506 

2,526,950 

(773,444) 

0- 

753,506 

(376,753) 

376,753 

177,074 

753,506 

354,148 

2047 

1,806,111 

2,653,298 

(847,186) 

0- 

806,111 

(403,056) 

403,056 

189,436 

806,111 

378,872 

Scenario four: 3% inflation, 7% property price increase

Finally, we assume inflation runs at 3% and the property market increases by 7% each year. In this case, the discount method results in a lower tax outcome than indexation. 

Property 

New CGT method 

Old CGT discounting method 

Company CGT 

 

Year of 
sale 

Property sale price 

Property 
indexed cost 

Gain on 
sale A 

A's tax @ 
47% 

Gain on 
sale 

Less 50% 
discount 

Taxable 
gain 

A's tax @ 
47% 

Gain for 
company 

Tax for A @ 
47% 

 

 

2027 

1,000,000 

1,000,000 

- 

- 

- 

- 

- 

- 

- 

- 

 

2028 

1,070,000 

1,030,000 

40,000 

18,800 

70,000 

(35,000) 

35,000 

16,450 

70,000 

32,900 

 

2029 

1,144,900 

1,060,900 

84,000 

39,480 

144,900 

(72,450) 

72,450 

34,052 

144,900 

68,103 

 

2030 

1,225,043 

1,092,727 

132,316 

62,189 

225,043 

(112,522) 

112,522 

52,885 

225,043 

105,770 

 

2031 

1,310,796 

1,125,509 

185,287 

87,085 

310,796 

(155,398) 

155,398 

73,037 

310,796 

146,074 

 

2032 

1,402,552 

1,159,274 

243,278 

114,340 

402,552 

(201,276) 

201,276 

94,600 

402,552 

189,199 

 

2033 

1,500,730 

1,194,052 

306,678 

144,139 

500,730 

(250,365) 

250,365 

117,672 

500,730 

235,343 

 

2034 

1,605,781 

1,229,874 

375,908 

176,677 

605,781 

(302,891) 

302,891 

142,359 

605,781 

284,717 

 

2035 

1,718,186 

1,266,770 

451,416 

212,166 

718,186 

(359,093) 

359,093 

168,774 

718,186 

337,548 

 

2036 

1,838,459 

1,304,773 

533,686 

250,832 

838,459 

(419,230) 

419,230 

197,038 

838,459 

394,076 

 

2037 

1,967,151 

1,343,916 

623,235 

292,920 

967,151 

(483,576) 

483,576 

227,281 

967,151 

454,561 

 

2038 

2,104,852 

1,384,234 

720,618 

338,690 

1,104,852 

(552,426) 

552,426 

259,640 

1,104,852 

519,280 

 

2039 

2,252,192 

1,425,761 

826,431 

388,422 

1,252,192 

(626,096) 

626,096 

294,265 

1,252,192 

588,530 

 

2040 

2,409,845 

1,468,534 

941,311 

442,416 

1,409,845 

(704,923) 

704,923 

331,314 

1,409,845 

662,627 

 

2041 

2,578,534 

1,512,590 

1,065,944 

500,994 

1,578,534 

(789,267) 

789,267 

370,956 

1,578,534 

741,911 

 

2042 

2,759,032 

1,557,967 

1,201,064 

564,500 

1,759,032 

(879,516) 

879,516 

413,372 

1,759,032 

826,745 

 

2043 

2,952,164 

1,604,706 

1,347,457 

633,305 

1,952,164 

(976,082) 

976,082 

458,758 

1,952,164 

917,517 

 

2044 

3,158,815 

1,652,848 

1,505,968 

707,805 

2,158,815 

(1,079,408) 

1,079,408 

507,322 

2,158,815 

1,014,643 

 

2045 

3,379,932 

1,702,433 

1,677,499 

788,425 

2,379,932 

(1,189,966) 

1,189,966 

559,284 

2,379,932 

1,118,568 

 

2046 

3,616,528 

1,753,506 

1,863,021 

875,620 

2,616,528 

(1,308,264) 

1,308,264 

614,884 

2,616,528 

1,229,768 

 

2047 

3,869,684 

1,806,111 

2,063,573 

969,879 

2,869,684 

(1,434,842) 

1,434,842 

674,376 

2,869,684 

1,348,752 

 

Caveats and key takeaways

These models are of course simplifications of the real world, in which inflation and market prices vary from year to year. They do highlight, however, that the indexation method does not always produce a higher tax bill for the taxpayer when compared to the discount method. In summary:

  • For a property market rising at least twice as fast as inflation, the discount method is preferable.
  • For a property market rising faster than inflation, but less than twice as fast, the lower tax outcome is somewhere between the two methods,
  • For a property market rising slower than inflation, the indexation method produces the lower tax outcome.
  • Holding a property in a company and paying a dividend always results in a higher tax amount. There are of course other reasons as to why holding property in a company may be preferable.

Ultimately, based on the specific assumptions and scenarios modeled above, we can conclude that the change to indexation does not necessarily place taxpayers in a worse position. Nor, by extension, does it place the government in a better position. Perhaps the government is banking on property prices increasing at twice the inflation rate to put them in the same position as before.

Not factored into the calculation is the minimum 30% tax amount payable on the capital gain under the new CGT rules. The study also does not consider other small business CGT discounts which may be available to individuals and trusts owning farmland.

None of this matters if the property is never sold, but ‘never’ is a really long time and whether it is this generation, the next or the one after, the changes to capital gains tax are impactful and extensive. What was once hallowed as a sacred pre-CGT asset, has changed with the stroke of a pen, and all properties will now need to deal with CGT.  

Whilst change is constant, these changes may create the impetus to review succession plans, freshen up old structures holding pre-CGT assets and plan for the future, at least until the next change.

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