The Government has been accused of being "spiteful" after announcing plans to stop public sector workers from automatically paying trade union subscriptions from their salaries.
The "check-off" practice was introduced at a time when many people did not have bank accounts, and before direct debits or internet payments existed.
Ministers say it is time to "get rid of this outdated practice and modernise the relationship between trade unions and their members".
Video report by ITV News Political Correspondent Emily Morgan:
Under the new proposals, to be included in the Trade Union Bill, subscriptions will have to be paid by direct debit from the employee's bank account.
Unions described it as a "political attack" on workers and warned the move will damage industrial relations.
Gail Cartmail, Unite assistant general secretary said: "This government will suffer a backlash from this, for people will see this for what it is - another needless, malicious attack on the people who are the backbone of our public services."
TUC assistant general secretary Paul Nowak said: "Instead of going out of their way to poison industrial relations, the government should engage positively with workers and their representatives for the good of public services and the economy."
"It's a totally unnecessary and vindictive move because it doesn't apply to any other salary based subscriptions like payments to charities", a spokesman for the Public and Commercial Services union said.
Labour also criticised the move as a "mean spirited and ideological attack on the rights of ordinary trade union members in the workplace."
Shadow Cabinet Office minister Jon Ashworth said the party were committed to "check-off" and called on the government to abandon plans to scrap the system.