The BBC has spent around £250,000 sending "bullying" letters to homes in Northern Ireland that do not have a TV licence.
The expenditure is equivalent to 1,600 TV licences.
Critics branded it a "ridiculous waste of money".
It follows revelations that almost a million letters had been fired off to households here between last March and the end of December.
It led to criticism of a heavy-handed approach when many families have struggled with the Covid-19 crisis.
The TV licence - which is due to rise from £157.50 to £159 from April - is required by any household watching or recording programmes as they are broadcast.
The BBC contracts TV Licensing inspectors for licence fee collection and enforcement.
Those whose cases are pursued risk a court prosecution and a fine of up to £1,000 plus costs and an offender levy.
On Monday the Belfast Telegraph reported that, between March 16 and December 31 last year, 1,133 defendants were dealt with by courts here for not having a TV licence.
The BBC, through TV Licensing, is also chasing unlicensed homes, with 945,994 letters sent in a similar period to addresses here.
The details were released after a Freedom of Information request.
The letters, emblazoned with red capital letters, threaten that inspectors are investigating why that address has no licence and warn of a potential £1,000 fine.
The BBC was asked to detail the cost of sending these letters but refused to do so, saying the information was commercially sensitive.
It did, however, confirm that the average cost of posting each letter was 27p. Based on that figure, the cost will be at least £255,400.
Across the UK, some 26,499,693 letters were issued between March and December 2020. On the same cost basis, the bill would top £7m.
Joe Ventre of the TaxPayers' Alliance, a right-wing spending watchdog, said: "These bullying BBC letters represent a ridiculous waste of money.
"People are being chased for an ever more expensive TV tax, at a time when hard-pressed households are struggling to make ends meet.
"BBC bosses need to stop this callous insistence on collecting cash via the criminal licence fee."
The BBC confirmed the number of letters issued to households has been increasing year-on-year. In 2016/17, 977,803 letters were sent to addresses here, rising to 1,243,425 by 2019/20. Around the UK, it increased from 28,592,886 in 2016/17 to 34,301,989 in 2019/20.
A TV Licensing spokesperson said: "Letters are a cost effective way to inform people of changes to their licence and encourage those who need to buy a licence to do so. TV Licensing mailings generate more revenue than they cost and help us in our duty to enforce the law."
People Before Profit MLA Gerry Carroll said it was "morally repugnant" that the BBC continued to issue warning letters during a global pandemic.
He said: "The last thing we need is more worry heaped at people's doors through the issuing of these unnecessary and ill-thought-out letters."
Mr Carroll has urged people who received a letter to contact him.