two combo of words set
1) pay for work - here the employee is regular, have to attend all days, fixed duty hours, eligible for all workmen benefits, OT etc also
2) pay to work - here the employee is not regular, have to attend for any stipulated date, can work for hours as he /she wish, but complete the job domain as his/ her ease , consultants / lawyer / CA are not regular employee of establishment, though they do all work of whole year, but just finalizing the work / filing returns etc, which is not done on daily basis. may b e for full day job for whole month or may be few hours job in month, they are not enrolled in payroll / attendance register
in short the consultant is treated at par to do work, like plumber, electrician or other misc works which are needed by industry, at regular "intervals",
to make claim of maternity benefit, employee has to be regular employee from certain period in past, ESIC/EPF may not be deducted, if the gross payout is over 21000 per month, but attendance matters
normally in such incidents employers seek invoice or bills, from consultant, on which TDS is deducted u/s 194 C of IT act
calculate your position in establishment, then proceed further for claim