10. Is there a ban on donations from corporations with government contracts to candidates?

207 Interpretation […]
(2) In this subpart and subparts 4 to 6 of this Part, unless the context otherwise
requires,— […]
candidate donation means a donation (whether of money or of the equivalent
of money or of goods or services or of a combination of those things) that is
made to a candidate, or to any person on the candidate’s behalf, for use in the
candidate’s campaign for election and—
(a) includes,—
(i) where goods or services are provided by a New Zealand person to
a candidate, or to any person on the candidate’s behalf, under a
contract or arrangement at a value less than their reasonable market
value, the latter being a value that exceeds $300, the amount
of the difference between the former value and the reasonable
market value of those goods or services; and […]
New Zealand person means a person who is not an overseas person
overseas person means—
(a) an individual who—
(i) resides outside New Zealand; and
(ii) is not a New Zealand citizen or registered as an elector; or
(b) a body corporate incorporated outside New Zealand; or
(c) an unincorporated body that has its head office or principal place of
business outside New Zealand
Source: Art. 207(2), Electoral Act 1993, (amended 2020)

There no explicit ban on donations from corporations with government contracts.