Close to 100,000 homeowners rushed to register for the property tax over the Bank Holiday weekend as the first deadline hit.
Over 500,000 houses are now registered for the tax as the Revenue Commissioners' campaign kicks in.
The last-minute surge in registrations means just short of one in three homes are now signed up for payment.
The deadline for registration by post passed yesterday, but the Revenue will accept forms today that have yesterday's postmark.
The publicity around the passing of the first deadline prompted 100,000 homeowners into action over the weekend.
Revenue said the number of registrations over the Bank Holiday was "close to 100,000, on top of the 400,000 already".
"The 100,000 includes post, online and online returns completed via the LPT (Local Property Tax) helpline," a spokesperson said.
And this figure is expected to rise further today as the remainder of the weekend post arrives. Anyone who didn't register yet has another three weeks to do so via the website or the LPT helpline number of 1890 200 255.
The deadline to register online is May 28, and the tax will be collected from July 1.
Revenue is responsible for registering and collecting the tax for the 1.66 million households in the country.
A team of up to 400 staff will be employed by the Revenue Commissioners to begin collecting the property tax from this July.
Homeowners who refuse to pay will have the money deducted from their bank accounts.
PAYE workers and pensioners will be the first to be hit under a tough regime, followed by those in receipt of state payments.
Revenue will use the database of 1.2 million people who have paid the household charge to identify offenders.
They will compare the names and addresses of those who have paid the €100 charge against a list of people sent property tax demand letters, and identify people who have failed to file a return.
The passing of the first registration deadline has also resulted in a wave of payments of the old household charge.
Homeowners who dodged the €100 charge are being flushed out by fears they will be targeted by the taxman.
The Revenue Commissioners will take over responsibility for collecting both taxes from July 1, and has promised to chase any tax evaders.
In the past week alone, almost 20,000 homeowners have paid the household charge – a massive surge.
Government sources say the rise in household charge payments is down to the fear of Revenue being on their trail – and the risk of having all their income audited. Revenue is expected to target those who failed to pay the charge in the first wave of enforcement.