Buy-to-let landlords enjoyed total annual returns of 12.2% over the past year helped by the flurry of purchases in the run-up to the stamp duty deadline on 1 April.
Average rents across England and Wales also rose 3% over the last year, to stand at £791 a month.
Rents rose fastest in the Midlands to hit £597 a month in the West Midlands and £613 in East Midlands
A minority of tenants still feeling financial squeeze, with 9.1% of rent in arrears, up from 8.8% last month
Existing landlords enjoyed an unexpected financial bonus from Chancellor George Osborne's stamp duty hike, according to the latest Buy-to-Let Index from Your Move and Reeds Rains.
Total annual growth of 12.2% from rental income and capital growth is a clear jump from the 10.7% seen in the year to February.
It is also the fastest annual rate of return for existing landlords since November 2014.
In absolute terms this means that the average landlord in England and Wales has seen a return of £22,135 over the year to March, before deductions such as property maintenance and mortgage payments.
Of this, the average capital gain contributed £13,494 while rental income made up £8,641.
Adrian Gill, director of lettings agents Your Move and Reeds Rains, said: “New tax changes intended to benefit owner-occupiers are now making it more expensive to become a landlord, at least for the time being.
“This has driven an extra wedge between those aspiring landlords planning to invest in additional homes to let, and those existing landlords who have already built up their portfolios.
“That difference will not last for long. But by making it more expensive to invest in property, it will hamper the healthy growth of the private rented sector.”