The votes open today, after more than two thirds of staff rejected offers on pay and pensions during the summer.
The pay deal from university employers would mean a below-inflation rise of just 1.8% for most staff, according to UNISON.
Many university employees would also pay more under recent changes being proposed to their pension scheme, says the union.
Pension reforms are to blame, adds UNISON, for rising contributions. First introduced in 2011, they were already likely to leave staff tens of thousands out of pocket. These new proposals mean staff have to pay in more and more just to retain their already reduced benefits.
UNISON head of education Jon Richards said: "Yet again university employers are fobbing off higher education staff with a below-inflation wage increase and a cut to pensions.
"Vice chancellors' and other senior managers’ pay packets continue to swell. But they won't stump up for all the other staff who make universities world class, despite being pushed hard for a decent pay rise.
"Their mediocre offer will do nothing to help staff, especially the lowest paid who are struggling to get by on poverty wages."
The pay claim from unions including UNISON included an amount to meet inflation plus 3% or a minimum increase of £3,349 to catch up for a decade of below inflation rises.
Both ballots open today (Monday) and close on Wednesday 30 October 2019.